System and method of identifying random access response

ABSTRACT

A communication method and system for converging a 5th-Generation (5G) communication system for supporting higher data rates beyond a 4th-Generation (4G) system with a technology for Internet of Things (IoT) is provided. The communication method and system include intelligent services based on the 5G communication technology and the IoT-related technology, such as smart home, smart building, smart city, smart car, connected car, health care, digital education, smart retail, security and safety services. A method includes transmitting a random access preamble on a physical random access channel (PRACH) transmission occasion from a base station, identifying a random access radio network temporary identifier (RA-RNTI) for receiving random access response (RAR) information based on a time related parameter, a frequency related parameter and an uplink carrier related parameter, and receiving scheduling assignment information scheduling a physical downlink shared channel (PDSCH) on a physical downlink control channel (PDCCH) based on the identified RA-RNTI from the base station.

CROSS-REFERENCE TO RELATED APPLICATION(S)

This application is a continuation application of prior application Ser.No. 17/122,220, filed on Dec. 15, 2020, which will be issued as U.S.Pat. No. 11,432,340 on Aug. 30, 2022; which is a continuationapplication of prior application Ser. No. 16/000,339, filed on Jun. 5,2018, which has issued as U.S. Pat. No. 10,904,921 on Jan. 26, 2021;which is based on and claimed priority under 35 U.S.C. § 119(a) of anIndian Provisional patent application number 201711020022, filed on Jun.7, 2017, in the Indian Patent Office, and of an Indian Provisionalpatent application number 201711025575, filed on Jul. 19, 2017, in theIndian Patent Office, and of an Indian Provisional patent applicationnumber 201711039948, filed on Nov. 9, 2017, in the Indian Patent Office,the disclosure of each of which is incorporated by reference herein inits entirety.

BACKGROUND 1. Field

The disclosure relates to a wireless communication system. Moreparticularly, the disclosure relates to a method and apparatus forperforming random access procedure.

2. Description of the Related Art

To meet the demand for wireless data traffic having increased sincedeployment of a fourth generation (4G) communication systems, effortshave been made to develop an improved fifth generation (5G) or pre-5Gcommunication system. Therefore, the 5G or pre-5G communication systemis also called a ‘Beyond 4G Network’ or a ‘Post long-term evolution(LTE) System.’ The 5G communication system is considered to beimplemented in higher frequency (mmWave) bands, e.g., 60 GHz bands, soas to accomplish higher data rates. To decrease propagation loss of theradio waves and increase the transmission distance, the beamforming,massive multiple-input multiple-output (MIMO), full dimensional MIMO(FD-MIMO), array antenna, an analog beam forming, large scale antennatechniques are discussed in 5G communication systems. In addition, in 5Gcommunication systems, development for system network improvement isunder way based on advanced small cells, cloud radio access networks(RANs), ultra-dense networks, device-to-device (D2D) communication,wireless backhaul, moving network, cooperative communication,coordinated multi-Points (CoMP), reception-end interference cancellationand the like. In the 5G system, Hybrid FSK and QAM Modulation (FQAM) andsliding window superposition coding (SWSC) as an advanced codingmodulation (ACM), and filter bank multi carrier (FBMC), non-orthogonalmultiple access (NOMA), and sparse code multiple access (SCMA) as anadvanced access technology have been developed.

The Internet, which is a human centered connectivity network wherehumans generate and consume information, is now evolving to the Internetof Things (IoT) where distributed entities, such as things, exchange andprocess information without human intervention. The Internet ofeverything (IoE), which is a combination of the IoT technology and theBig Data processing technology through connection with a cloud server,has emerged. As technology elements, such as “sensing technology,”“wired/wireless communication and network infrastructure,” “serviceinterface technology,” and “security technology” have been demanded forIoT implementation, a sensor network, a machine-to-machine (M2M)communication, machine type communication (MTC), and so forth have beenrecently researched. Such an IoT environment may provide intelligentInternet technology services that create a new value to human life bycollecting and analyzing data generated among connected things. IoT maybe applied to a variety of fields including smart home, smart building,smart city, smart car or connected cars, smart grid, health care, smartappliances and advanced medical services through convergence andcombination between existing information technology (IT) and variousindustrial applications.

In line with this, various attempts have been made to apply 5Gcommunication systems to IoT networks. For example, technologies such asa sensor network, MTC, and M2M communication may be implemented bybeamforming, MIMO, and array antennas. Application of a cloud radioaccess network (RAN) as the above-described Big Data processingtechnology may also be considered to be as an example of convergencebetween the 5G technology and the IoT technology.

In the existing wireless communication system i.e. in LTE, random access(RA) procedure is used to achieve uplink time synchronization. RAprocedure is used in LTE during initial access, handover, radio resourceconnection (RRC) connection re-establishment procedure, positioningpurpose, scheduling request transmission, a secondary cell group (SCG)addition/modification and data or control information transmission inuplink by non-synchronized user equipment (UE) in RRC CONNECTED state.Recently a third generation partnership project (3GPP) standard grouphas initiated to develop new wireless communication system i.e. newradio (NR). In NR, a need exists for providing enhanced RA procedure inconsideration of characteristics of NR.

The above information is presented as background information only toassist with an understanding of the disclosure. No determination hasbeen made, and no assertion is made, as to whether any of the abovemight be applicable as prior art with regard to the disclosure.

SUMMARY

Aspects of the disclosure are to address at least the above mentionedproblems and/or disadvantages and to provide at least the advantagesdescribed below. Accordingly, an aspect of the disclosure is to providean apparatus and method for performing random access procedure.

Additional aspects will be set forth in part in the description whichfollows and, in part, will be apparent from the description, or may belearned by practice of the presented embodiments.

In accordance with an aspect of the disclosure, a method in a wirelesscommunication system is provided. The method includes transmitting arandom access preamble on a physical random access channel (PRACH)transmission occasion from a base station, identifying a random accessradio network temporary identifier (RA-RNTI) for receiving random accessresponse (RAR) information based on an orthogonal frequency divisionmultiplexing (OFDM) symbol related parameter, slot related parameter, afrequency related parameter, and an uplink carrier related parameter,and receiving scheduling assignment information scheduling a physicaldownlink shared channel (PDSCH) on a physical downlink control channel(PDCCH) based on the identified RA-RNTI from the base station.

In accordance with another aspect of the disclosure, a method in awireless communication system is provided. The method includes receivinga random access preamble on a PRACH transmission occasion from aterminal, identifying a RA-RNTI for transmitting RAR information basedon a OFDM symbol related parameter, slot related parameter, a frequencyrelated parameter and an uplink carrier related parameter, generatingscheduling assignment information scheduling a PDSCH and transmittingthe scheduling assignment information on a PDCCH based on the identifiedRA-RNTI to the terminal.

In accordance with another aspect of the disclosure, a terminal in awireless communication system is provided. The UE includes atransceiver, and a controller coupled with the transceiver andconfigured to control to, transmit a random access preamble on a PRACHtransmission occasion from a base station, identify a RA-RNTI forreceiving RAR information based on a OFDM symbol related parameter, aslot related parameter, a frequency related parameter and an uplinkcarrier related parameter, and receive scheduling assignment informationscheduling a PDSCH on a PDCCH based on the identified RA-RNTI from thebase station.

In accordance with another aspect of the disclosure, a base station in awireless communication system is provided. The base station includes atransceiver, and a controller coupled with the transceiver andconfigured to control to, receive a random access preamble on a PRACHtransmission occasion from a terminal, identify a RA-RNTI fortransmitting RAR information based on a OFDM symbol related parameter, aslot related parameter, a frequency related parameter and an uplinkcarrier related parameter, generate scheduling assignment informationscheduling a PDSCH, and transmit the scheduling assignment informationon a PDCCH based on the identified RA-RNTI to the terminal.

Other aspects, advantages, and salient features of the disclosure willbecome apparent to those skilled in the art from the following detaileddescription, which, taken in conjunction with the annexed drawings,discloses various embodiments of the disclosure.

BRIEF DESCRIPTION OF THE DRAWINGS

The above and other aspects, features, and advantages of certainembodiments of the disclosure will be more apparent from the followingdescription taken in conjunction with the accompanying drawings, inwhich:

FIG. 1 illustrates a contention-based random access (CBRA) procedureaccording to an embodiment of the disclosure;

FIG. 2 illustrates a contention-free random access (CFRA) procedureaccording to an embodiment of the disclosure;

FIG. 3 illustrates a random access response (RAR) window for receivingRARs in a random access (RA) procedure according to an embodiment of thedisclosure;

FIGS. 4A and 4B illustrate example methods of receiving RARs accordingto various embodiments of the disclosure;

FIG. 5 illustrates a method by a user equipment (UE) to determinesuccessfully receiving a RAR corresponding to a physical random accesschannel (PRACH) preamble that is transmitted by the UE according to anembodiment of the disclosure;

FIG. 6 illustrates a method by a UE to determine successfully receivinga RAR corresponding to a PRACH preamble that is transmitted by the UEaccording to an embodiment of the disclosure;

FIGS. 7A and 7B illustrate example methods of receiving RARs accordingto various embodiments of the disclosure;

FIG. 8 illustrates the UE operation in an embodiment of the disclosureto determine that the UE has successfully received the RAR correspondingto physical random access channel (PRACH) preamble transmitted by the UEas follows according to an embodiment of the disclosure;

FIG. 9 illustrates a method by a UE to determine successfully receivinga RAR corresponding to a PRACH preamble that is transmitted by the UEaccording to an embodiment of the disclosure;

FIGS. 10A and 10B illustrate example methods of receiving RARs accordingto various embodiments of the disclosure;

FIG. 11 illustrates a method by a UE to determine successfully receivinga RAR corresponding to a PRACH preamble that is transmitted by the UEaccording to an embodiment of the disclosure;

FIG. 12 illustrates a method by a UE to determine successfully receivinga RAR corresponding to PRACH preamble transmitted by the UE according toan embodiment of the disclosure;

FIGS. 13A and 13B illustrate example methods of receiving RARs accordingto various embodiments of the disclosure;

FIG. 14A illustrates a method by a UE to determine successfullyreceiving a RAR corresponding to a PRACH preamble that is transmitted bythe UE according to an embodiment of the disclosure;

FIG. 14B illustrates a method by a UE to determine successfullyreceiving a RAR corresponding to a PRACH preamble that is transmitted bythe UE according to an embodiment of the disclosure;

FIG. 15 illustrates a RAR media access control (MAC) protocol data unit(PDU) structure according to an embodiment of the disclosure;

FIGS. 16A and 16B illustrate various embodiments of a type field in aMAC subheader according to various embodiments of the disclosure;

FIG. 17A illustrates another RAR MAC PDU structure according to anembodiment of the disclosure;

FIG. 17B illustrates another RAR MAC PDU structure according to anembodiment of the disclosure.

FIG. 17C illustrates a type field in a MAC subheader according to anembodiment of the disclosure;

FIG. 18 illustrates another RAR MAC PDU structure according to anembodiment of the disclosure;

FIG. 19 illustrates an embodiment of indexing slots for computing aRA-radio network temporary identifier (RA-RNTI) according to anembodiment of the disclosure;

FIG. 20 illustrates another embodiment of indexing slots for computing aRA-RNTI according to an embodiment of the disclosure;

FIG. 21 illustrates another embodiment of indexing slots for computing aRA-RNTI according to an embodiment of the disclosure;

FIG. 22 illustrates another embodiment of indexing slots for computing aRA-RNTI according to various embodiments of the disclosure;

FIG. 23 illustrates another embodiment of indexing slots for computingRA-RNTI according to an embodiment of the disclosure;

FIG. 24 illustrates transmitting a random access preamble identifier toa UE according to an embodiment of the disclosure;

FIGS. 25 and 26 illustrate transmitting a random access preambleidentifier to UE according to an embodiment of the disclosure;

FIG. 27 illustrates an evolved Node B (eNB) according to an embodimentof the disclosure; and

FIG. 28 illustrates a UE according to an embodiment of the disclosure.

Throughout the drawings, it should be noted that like reference numbersare used to depict the same or similar elements, features, andstructures.

DETAILED DESCRIPTION

The following description with reference to the accompanying drawings isprovided to assist in a comprehensive understanding of variousembodiments of the disclosure as defined by the claims and theirequivalents. It includes various specific details to assist in thatunderstanding but these are to be regarded as merely exemplary.Accordingly, those of ordinary skill in the art will recognize thatvarious changes and modifications of the various embodiments describedherein can be made without departing from the scope and spirit of thedisclosure. In addition, descriptions of well-known functions andconstructions may be omitted for clarity and conciseness.

The terms and words used in the following description and claims are notlimited to the bibliographical meanings, but, are merely used by theinventor to enable a clear and consistent understanding of thedisclosure. Accordingly, it should be apparent to those skilled in theart that the following description of various embodiments of thedisclosure is provided for illustration purpose only and not for thepurpose of limiting the disclosure as defined by the appended claims andtheir equivalents.

It is to be understood that the singular forms “a,” “an,” and “the”include plural referents unless the context clearly dictates otherwise.Thus, for example, reference to “a component surface” includes referenceto one or more of such surfaces.

In each drawing, the same or similar components may be denoted by thesame reference numerals.

Each block of the flow charts and combinations of the flow charts may beperformed by computer program instructions. Because these computerprogram instructions may be mounted in processors for a generalcomputer, a special computer, or other programmable data processingapparatuses, these instructions executed by the processors for thecomputer or the other programmable data processing apparatuses createmeans performing functions described in block(s) of the flow charts.Because these computer program instructions may also be stored in acomputer usable or computer readable memory of a computer or otherprogrammable data processing apparatuses in order to implement thefunctions in a specific scheme, the computer program instructions storedin the computer usable or computer readable memory may also producemanufacturing articles including instruction means performing thefunctions described in block(s) of the flow charts. Because the computerprogram instructions may also be mounted on the computer or the otherprogrammable data processing apparatuses, the instructions performing aseries of operation steps on the computer or the other programmable dataprocessing apparatuses to create processes executed by the computer tothereby execute the computer or the other programmable data processingapparatuses may also provide steps for performing the functionsdescribed in block(s) of the flow charts.

In addition, each block may indicate a module, a segment, and/or a codeincluding one or more executable instructions for executing a specificlogical function(s). Further, functions mentioned in the blocks occurregardless of a sequence in some alternative embodiments. For example,two blocks that are consecutively illustrated may be simultaneouslyperformed in fact or be performed in a reverse sequence depending oncorresponding functions sometimes.

Herein, the term “unit” may include software and/or hardware components,such as a field-programmable gate array (FPGA) and/or anapplication-specific integrated circuit (ASIC). However, the meaning of“unit” is not limited to software and/or hardware. For example, a unitmay be configured to be in a storage medium that may be addressed andmay also be configured to reproduce one or more processor. Accordingly,a “unit” may include components such as software components, objectoriented software components, class components, task components,processors, functions, attributes, procedures, subroutines, segments ofprogram code, drivers, firmware, microcode, circuit, data, database,data structures, tables, arrays, and variables.

Functions provided in the components and the “units” may be combinedwith a smaller number of components and/or “units” or may furtherseparated into additional components and/or “units.”

In addition, components and units may also be implemented to reproduceone or more central processing units (CPUs) within a device or asecurity multimedia card.

The terms as used in the disclosure are provided to describe specificembodiments, and do not limit the scope of other embodiments. It is tobe understood that singular forms include plural forms unless thecontext clearly dictates otherwise. Unless otherwise defined, the termsand words including technical or scientific terms used in the followingdescription and claims may have the same meanings as generallyunderstood by those skilled in the art. The terms as generally definedin dictionaries may be interpreted as having the same or similarmeanings as the contextual meanings of related technology. Unlessotherwise defined, the terms should not be interpreted as ideally orexcessively formal meanings. When needed, even the terms as defined inthe disclosure may not be interpreted as excluding embodiments of thedisclosure.

Herein, a base station performs resource allocation to a terminal.Examples of the base station may include a base station, a Node B, anevolved Node B (eNB), a wireless access unit, a base station controller,a node on a network, etc. Examples of the terminal may include a userequipment (UE), a mobile station (MS), a cellular phone, a smart phone,a computer, a multimedia system performing a communication function,etc.

Herein, a downlink (DL) is a radio transmission path of a signal from abase station to a UE and an uplink (UL) is a radio transmission path ofa signal from the UE to the base station.

The embodiments of the disclosure may be applied to other communicationsystems having similar technical backgrounds or channel forms.

In the recent years several broadband wireless technologies have beendeveloped to meet the growing number of broadband subscribers and toprovide more and better applications and services. The second generationwireless communication system has been developed to provide voiceservices while ensuring the mobility of users. Third generation wirelesscommunication system supports not only the voice service but also dataservice. In recent years, the fourth wireless communication system hasbeen developed to provide high-speed data service. However, currently,the fourth generation wireless communication system suffers from lack ofresources to meet the growing demand for high speed data services. Sofifth generation wireless communication system is being developed tomeet the growing demand for high speed data services, supportultra-reliability and low latency applications.

The fifth generation wireless communication system will be implementednot only in lower frequency bands but also in higher frequency (mmWave)bands, e.g., 10 GHz to 100 GHz bands, so as to accomplish higher datarates. To mitigate propagation loss of the radio waves and increase thetransmission distance, the beamforming, massive multiple-inputmultiple-output (MIMO), full dimensional MIMO (FD-MIMO), array antenna,an analog beam forming, large scale antenna techniques are beingconsidered in the design of fifth generation wireless communicationsystem. In addition, the fifth generation wireless communication systemis expected to address different use cases having quite differentrequirements in terms of data rate, latency, reliability, mobility etc.However, it is expected that the design of the air-interface of thefifth generation wireless communication system would be flexible enoughto serve the UEs having quite different capabilities depending on theuse case and market segment the UE cater service to the end customer.Few example use cases the fifth generation wireless communication systemwireless system is expected to address is enhanced mobile broadband(eMBB), massive machine type communication (m-MTC), ultra-reliable lowlatency communication (URLL) etc. The eMBB requires multiple Gigabytes(Gbps) of data rate, low latency, high mobility so on and so forthaddress the market segment representing the conventional wirelessbroadband subscribers needing internet connectivity everywhere, all thetime and on the go. The m-MTC requirements like very high connectiondensity, infrequent data transmission, very long battery life, lowmobility address so on and so forth address the market segmentrepresenting the Internet of Things (IoT)/Internet of Everything (IoE)envisioning connectivity of billions of devices. The URLL requirementslike very low latency, very high reliability and variable mobility so onand so forth address the market segment representing the Industrialautomation application, vehicle-to-vehicle/vehicle-to-infrastructurecommunication foreseen as one of the enabler for autonomous cars.

In the existing wireless communication system (e.g., long term evolution(LTE)), a random access (RA) procedure is used to achieve uplink timesynchronization. The RA procedure is used in LTE during initial access,handover, a radio resource connection (RRC) re-establishment procedure,positioning purpose, scheduling request transmission, a secondary cellgroup (SCG) addition/modification and data or control informationtransmission in uplink by non-synchronized UE in RRC CONNECTED state. InLTE two types of RA procedure are defined: contention-based andcontention-free.

FIG. 1 illustrates a contention-based random access (CBRA) procedureaccording to an embodiment of the disclosure.

Referring to FIG. 1 , the contention-based RA procedure includes 4operation. In operation 100 (RA Preamble Transmission), a UE selects oneof the available 64-Ncf contention based RA preambles. Ncf is the numberof RA preambles reserved for contention free access. The contentionbased RA preambles can be optionally partitioned into two groups. If twogroups are configured, the UE selects the group based on size of message3 it can transmit. The initial RA preamble transmission power is setbased on open loop estimation after compensating for path loss.

In operation 110 (RA Response (RAR)), an eNB transmits the RAR onphysical downlink shared channel (PDSCH) addressed to RA-radio networktemporary identifier (RNTI). The RA-RNTI identifies the time-frequencyslot in which RA preamble was detected by eNB. The RAR conveys a RApreamble identifier, timing alignment information, a temporary cell-RNTI(C-RNTI) and UL grant for message 3. The RAR may also include back offindicator to instruct a UE to back off for period of time beforeretrying RA attempt. The RAR is transmitted in RAR window.

FIG. 3 illustrates a random access response (RAR) window for receivingRARs in a RA procedure according to an embodiment of the disclosure.

Referring to FIG. 3 , a RAR window 310 starts at subframe ‘x+3’ for RApreamble 300 transmitted in subframe ‘x’ to receive a RAR 320. A RARwindow size is configurable.

In operation 120 (Scheduled UL Transmission on UL shared channel (SCH)),scheduled UL transmission is used to transmit message such as radioresource connection (RRC) Connection Request, RRC ConnectionRe-establishment request, RRC handover confirm, scheduling requestmessage, etc. It also includes the UE identity (i.e. cell-radio networktemporary identifier (C-RNTI) or SAE-temporary mobile subscriberidentity (S-TMSI) or a random number). A hybrid automatic request repeat(HARQ) is used for this transmission. Referring to FIG. 3 , this iscommonly referred as MSG3 330.

In operation 130 (Contention Resolution Message), the contentionresolution message uses HARQ and is addressed to C-RNTI (if included inmessage 3) or temporary C-RNTI (UE identity included in message 3 isincluded this case). On successful decoding of this message, HARQfeedback is only sent by UE which detects its own UE ID (or C-RNTI).

FIG. 2 illustrates a contention-free RA (CFRA) procedure according to anembodiment of the disclosure.

Referring to FIG. 2 , a CFRA procedure is used for scenarios such ashandover where low latency is required, timing advance establishment forS Cell, etc. The differences of the contention-free RA from thecontention-based RA are as follows:

-   -   eNB assigns to UE non-contention RA preamble in dedicated        signaling in operation 200.    -   UE transmits the assigned non-contention RA preamble in        operation 210.    -   ENB transmits the RAR on PDSCH addressed to RA-RNTI. RAR conveys        RA preamble identifier and Timing alignment information. RAR may        also include UL grant. RAR is transmitted in RAR window similar        to contention based RA procedure. Contention free RA procedure        terminates after receiving the RAR in operation 220.

When a UE is configured with carrier aggregation, RA procedure can beperformed on primary cell (PCell) as well as secondary cell (SCell). Incase of SCell only CFRA procedure is used. RA procedure for SCell isonly initiated by network. When performing RA procedure on the PCell, aUE transmits the random access channel (RACH) preamble on PCell andreceives the corresponding RAR on PCell. When performing CFRA on theSCell, UE transmits the RACH preamble on SCell and receives thecorresponding RAR on PCell. It is to be noted that RACH configuration(RACH resources and parameters) is cell specific. PCell and SCell havetheir own RACH configuration.

Consider two cells, Cell 1 (Frequency F1) and Cell 2 (F2). UE 1 isconfigured with carrier aggregation (CA) where Cell 1 is PCell and Cell2 is SCell. UE 1 is assigned a dedicated preamble P1 for RACHtransmission on SCell. UE 1 transmits RACH preamble P1 in RACH resource(e.g. time index (t_id) of RACH resource: 5, Index (f_id) of frequencyresource: 0) on SCell i.e. Cell 2. RACH resource in time domain israndomly selected from RACH configuration of cell 2. UE 1 waits for RARon cell 1 during RAR window. For receiving RAR, UE 1 monitors forphysical downlink control channel (PDCCH) masked with RA-RNTI: 6(1+t_id+10*f_id). Another UE (called UE2) transmits RACH preamble P1 inRACH resource (e.g. time index (t_id) of RACH resource: 5, Index (f_id)of frequency resource: 0) on PCell i.e. Cell 1. RACH resource israndomly selected from RACH configuration of cell 1. UE 2 waits for RARon cell 1 during RAR window. For receiving RAR, UE 2 monitors for PDCCHmasked with RA-RNTI: 6 (1+t_id+10*f_id). In this scenario, followingcases can happen:

In Case 1, Preamble P1 may be received by eNB on both cell 1 and cell 2.In this case, RAR is transmitted over cell 1 by eNB. RAR is received byboth UE1 and UE2. Both consider RAR reception as successful. However, TAvalue can be different for UE1 and UE2. So each UE should processdifferent RAR. UE1 and UE2 cannot distinguish the RAR as random accesspreamble identifier (RAPID) and RA-RNTI is same for both UEs, even iftwo RARs are transmitted.

In Case 2, Preamble P1 may be received by eNB on cell 1 and not on cell2. In this case, RAR is transmitted over cell 1 by eNB. RAR is receivedby both UE1 and UE2. Both consider RAR reception as successful. However,RAR is not meant for UE 2; still it considers RAR reception successful.

In Case 3, Preamble P1 may be received by eNB on cell 2 and not on cell1, In this case, RAR is transmitted over cell 1 by eNB. RAR is receivedby both UE1 and UE2. Both considers RAR reception as successful.However, RAR is not meant for UE1; still it considers RAR receptionsuccessful.

So enhancement of RA procedure is needed to enable UEs to correctlyidentify the RAR.

Identification of Random Access Response

Method 1

In one method of the disclosure it is proposed to add one bit indicator(referred as ‘OtherCellIndicator’) in random access response (RAR).‘OtherCellIndicator’ may be added in the medium access control (MAC)header (i.e. MAC subheader for RAR) or MAC payload (i.e. MAC RAR).

The ‘OtherCellIndicator’ is set to one in RAR, if cell is transmittingthis RAR for a RACH preamble (or MSG 1) received on another cell. FromUE perspective, if the ‘OtherCellIndicator’ is set to one in RARreceived from a cell, then it means that this RAR corresponds to RACHpreamble (or MSG1) transmitted on another cell. The ‘OtherCellIndicator’is set to zero in RAR, if cell is transmitting this RAR for a RACHpreamble received on this cell. From UE perspective, if the‘OtherCellIndicator’ is set to zero in RAR received from a cell, then itmeans that this RAR corresponds to RACH preamble (or MSG1) transmittedon this cell. In an alternate embodiment, instead of including‘OtherCellIndicator’ set to zero, ‘OtherCellIndicator’ field may not beincluded in RAR, if this RAR is for a RACH preamble received on thiscell

In an alternate embodiment of this method, ‘Type’ field in MAC subheadercorresponding to RAR may indicate whether the RAR received from a cellcorresponds to RACH preamble (or MSG1) transmitted on another cell orthe cell from which RAR is received.

FIGS. 4A and 4B illustrate example methods of receiving RARs accordingto various embodiments of the disclosure.

Referring to FIG. 4A, a UE 400 transmits RACH preamble to cell 1 410 inoperation 430. Cell 1 410 transmits the RAR corresponding to RACHpreamble received from the UE 400 in operation 440. Since the RARtransmitted by cell 1 410 corresponds to RACH preamble received from UE(400) on same cell, cell 1 410 sets ‘OtherCellIndicator’ to zero. In analternate embodiment, instead of including ‘OtherCellIndicator’ set tozero, cell 1 410 may not include ‘OtherCellIndicator’ field in RAR. Inan alternate embodiment of this method, cell 1 410 may set ‘Type’ fieldin MAC subheader to a value which indicate that this RAR corresponds toRACH preamble (or MSG1) transmitted on this cell.

Referring to FIG. 4B, a UE 400 transmits RACH preamble to cell 2 420 inoperation 460. Cell 1 410 transmits the RAR corresponding to RACHpreamble received from the UE 400 on cell 1 410 in operation 470. Oneexample of this scenario is the carrier aggregation, where the UE 400 isconfigured with Cell 2 420 as SCell and Cell 1 410 as PCell. In thiscase, RACH preamble is transmitted on SCell and the corresponding RAR isreceived by UE from PCell. Since the RAR transmitted by cell 1 410corresponds to RACH preamble received from UE 400 on different cell,cell 1 410 sets ‘OtherCellIndicator’ to one. In an alternate embodimentof this method, cell 1 410 may set ‘Type’ field in MAC subheader to avalue which indicate that this RAR corresponds to RACH preamble (orMSG1) transmitted on another cell.

FIG. 5 illustrates a method by a user equipment (UE) to determinesuccessfully receiving a RAR corresponding to a physical random accesschannel (PRACH) preamble that is transmitted by the UE according to anembodiment of the disclosure.

Referring to FIG. 5 , when a downlink assignment has been received onthe new radio-PDCCH (NR-PDCCH) for the RA-RNTI and the receivedtransport block (TB) is successfully decoded in operation 500, the UEidentifies whether the RAR contains RAPID corresponding to thetransmitted random access preamble or not in operation 510. If theRandom Access Response contains a Random Access Preamble identifiercorresponding to the transmitted Random Access Preamble, the UEidentifies whether the UE has transmitted random access preamble on thecell from which UE has received this RAR in operation 530. If thereceived RAR does not contain RAPID corresponding to the transmittedrandom access preamble, the UE shall continue monitoring for RAR untilthe end of RAR window in operation 520.

If the UE has transmitted random access preamble on the cell which UEhas received this RAR, the UE identifies whether OtherCelllndicator isset to zero in received RAR or not in operation 550 and the UE shallconsider this Random Access Response reception successful in operation570 if the OtherCelllndicator is set to zero. If the UE identifies thatit has transmitted random access preamble on other cell, the UEidentifies whether the OtherCelllndicator is set to one in received RARin operation 540. If the OtherCelllndicator is set to one, the UE shallconsider this RAR reception is successful in operation 570. In theoperation 540 if the UE identifies that the OtherCelllndicator is notset to one, the UE shall continue monitoring for RAR until the end ofthe RAR window in operation 560. In the operation 550 if the UEidentifies that the OtherCelllndicator is not set to zero, the UE shallcontinue monitoring for RAR until the end of the RAR window in operation560.

FIG. 6 illustrates a method by a UE to determine successfully receivinga RAR corresponding to a PRACH preamble that is transmitted by the UEaccording to an embodiment of the disclosure.

Referring to FIG. 6 , when a downlink assignment has been received onthe NR-PDCCH for the RA-RNTI and the received TB is successfully decodedin operation 600, the UE identifies whether the RAR contains RAPIDcorresponding to the transmitted random access preamble or not inoperation 610. If the Random Access Response contains a Random AccessPreamble identifier corresponding to the transmitted Random AccessPreamble, the UE identifies whether the UE has transmitted random accesspreamble on PCell or PSCell in operation 630. If the received RAR doesnot contain RAPID corresponding to the transmitted random accesspreamble, the UE shall continue monitoring for RAR until the end of RARwindow in operation 620.

If the UE has transmitted random access preamble on the PCell or PrimarySCell (PSCell), the UE identifies whether OtherCelllndicator is set tozero in received RAR or not in operation 650 and the UE shall considerthis Random Access Response reception successful in operation 670 if theOtherCelllndicator is set to zero. If the UE identifies that it has nottransmitted random access preamble on PCell or primary secondary cell(PSCell), the UE identifies whether the OtherCelllndicator is set to onein received RAR in operation 640. If the OtherCelllndicator is set toone, the UE shall consider this RAR reception is successful in operation670. In the operation 640 if the UE identifies that theOtherCelllndicator is not set to one, the UE shall continue monitoringfor RAR until the end of the RAR window in operation 660. In theoperation 650 if the UE identifies that the OtherCelllndicator is notset to zero, the UE shall continue monitoring for RAR until the end ofthe RAR window in operation 660.

In alternate embodiment of this method, OtherCelllndicator can beincluded in NR-PDCCH (i.e. in downlink control information (DCI))instead of RAR. In another embodiment, cell info (e.g. frequency orcarrier info) can be included in RAR when OtherCelllndicator is set toone. The UE operation in this case to determine that it has successfullyreceived the RAR corresponding to PRACH preamble transmitted by it asfollows.

When a downlink assignment has been received on the NR-PDCCH for theRA-RNTI and the received TB is successfully decoded, if the RandomAccess Response contains a Random Access Preamble identifiercorresponding to the transmitted Random Access Preamble, and if the UEhas transmitted random access preamble on PCell or PSCell and ifOtherCelllndicator is set to zero in received RAR, the UE shall considerthis Random Access Response reception successful.

If UE has transmitted random access preamble on SCell other than PSCelland OtherCelllndicator is set to one in received RAR and if carrier inforeceived in RAR matches with carrier on which UE has transmitted RACHpreamble, the UE shall consider this Random Access Response receptionsuccessful.

The UE operation in an embodiment of the proposed disclosure todetermine that it has successfully received the RAR corresponding toPRACH preamble transmitted by it as follows.

When a downlink assignment has been received on the NR-PDCCH for theRA-RNTI and the received TB is successfully decoded, if the RandomAccess Response contains a Random Access Preamble identifiercorresponding to the transmitted Random Access Preamble and if the UEhas transmitted random access preamble on the cell from which UE hasreceived this RAR and if OtherCelllndicator is set to zero in receivedRAR, the UE shall consider this Random Access Response receptionsuccessful.

If the UE has transmitted random access preamble on the cell other thanthe cell from which UE has received this RAR and if OtherCelllndicatoris set to one in received RAR and if carrier info received in RARmatches with carrier on which UE has transmitted RACH preamble, the UEshall consider this Random Access Response reception successful.

Method 2

In another method of the disclosure it is proposed to add one bitindicator (referred as ‘OtherCelllndicator’) in random access response(RAR). ‘OtherCelllndicator’ may be added in the MAC header (i.e. MACsubheader for RAR) or MAC payload (i.e. MAC RAR).

The ‘OtherCelllndicator’ is set to one in RAR, if cell is transmittingthis RAR for a RACH preamble (or MSG 1) received on another cell. FromUE perspective, if the ‘OtherCelllndicator’ is set to one in RARreceived from a cell, then it means that this RAR corresponds to RACHpreamble (or MSG1) transmitted on another cell. The ‘OtherCelllndicator’is set to zero in RAR, if cell is transmitting this RAR for a RACHpreamble received on this cell. From UE perspective, if the‘OtherCelllndicator’ is set to zero in RAR received from a cell, then itmeans that this RAR corresponds to RACH preamble (or MSG1) transmittedon this cell. In an alternate embodiment, instead of including‘OtherCelllndicator’ set to zero, ‘OtherCelllndicator’ field may not beincluded in RAR, if this RAR is for a RACH preamble received on thiscell

In an alternate embodiment of this method, ‘Type’ field in MAC subheadercorresponding to RAR may indicate whether the RAR received from a cellcorresponds to RACH preamble (or MSG1) transmitted on another cell orthe cell from which RAR is received.

In alternate embodiment of this method, OtherCelllndicator can beincluded in NR-PDCCH (i.e. in DCI) instead of RAR.

Additionally, it is propose that in addition to RAPID and RA-RNTIchecking, UE which has transmitted RACH preamble on another cell, alsochecks for its C-RNTI in RAR. If cell is transmitting RAR for a RACHpreamble (or MSG 1) received on another cell then it also includes UE'sC-RNTI in RAR. Since the RAR for RACH preamble (or MSG 1) received onanother cell is allowed only in case of contention-free RACH, networkknows the C-RNTI of UE which has transmitted the RACH preamble.

FIGS. 7A and 7B illustrate example methods of receiving RARs accordingto various embodiments of the disclosure.

Referring to FIG. 7A, a UE 700 transmits RACH preamble to cell 1 710 inoperation 730. The Cell 1 710 transmits the RAR corresponding to RACHpreamble received from UE 700 in operation 735. Since the RARtransmitted by cell 1 710 corresponds to RACH preamble received from theUE 700 on same cell, cell 1 710 sets ‘OtherCellIndicator’ to zero. In analternate embodiment, instead of including ‘OtherCellIndicator’ set tozero, cell 1 710 may not include ‘OtherCellIndicator’ field in RAR. Inan alternate embodiment of this method, cell 1 710 may set ‘Type’ fieldin MAC subheader to a value which indicate that this RAR corresponds toRACH preamble (or MSG1) transmitted on this cell. The UE 700 considersRAR reception successful if it corresponds to its RA-RNTI, RAPID and‘OtherCellIndicator’ set to zero or not present in RAR. In case ofcontention based RACH temporary C-RNTI is also included in RAR in thiscase. In case of contention free RACH, UE's C-RNTI may not be includedin this case. Therefore, the UE 700 can determine the RAR is receivedsuccessfully if the RAR corresponds UE's RA-RNTI, RAPID andOtherCelllndicator set to 0 or not present in the RAR in operation 740.

Referring to FIG. 7B, a UE 700 transmits RACH preamble to cell 2 720 inoperation 760. Cell 1 710 transmits the RAR corresponding to RACHpreamble received from the UE 700 on cell 1 710 in operation 765. Oneexample of this scenario is the carrier aggregation, where the UE 700 isconfigured with Cell 2 720 as SCell and Cell 1 710 as PCell. In thiscase, RACH preamble is transmitted on SCell and the corresponding RAR isreceived by UE from PCell. Since the RAR transmitted by cell 1 710corresponds to RACH preamble received from the UE 700 on different cell,cell 1 710 sets ‘OtherCellIndicator’ to one. In an alternate embodimentof this method, cell 1 710 may set ‘Type’ field in MAC subheader to avalue which indicate that this RAR corresponds to RACH preamble (orMSG1) transmitted on another cell. Cell 1 710 also includes UE's C-RNTIin RAR. RACH preamble and/or RACH resource on which RACH preamble isreceived by Cell 2 720 is assigned to the UE 700, so UE's C-RNTI isknown to network (or gNB or cell 2). Therefore, the UE 700 can determinethe RAR is received successfully if the RAR corresponds UE's RA-RNTI,RAPID, OtherCelllndicator set to 1 and received C-RNTI which matcheswith UE's C-RNTI in operation 770.

FIG. 8 illustrates the UE operation in an embodiment of the disclosureto determine that the UE has successfully received the RAR correspondingto physical random access channel (PRACH) preamble transmitted by the UEas follows according to an embodiment of the disclosure.

Referring to FIG. 8 , when a downlink assignment has been received onthe NR-PDCCH for the RA-RNTI and the received TB is successfully decodedin operation 800, the UE identifies whether the RAR contains RAPIDcorresponding to the transmitted random access preamble or not inoperation 810. If the Random Access Response contains a Random AccessPreamble identifier corresponding to the transmitted Random AccessPreamble, the UE identifies whether the UE has transmitted random accesspreamble on the cell from which UE has received this RAR in operation830. If the received RAR does not contain RAPID corresponding to thetransmitted random access preamble, the UE shall continue monitoring forRAR until the end of RAR window in operation 820.

If the UE has transmitted random access preamble on the cell which UEhas received this RAR, the UE identifies whether OtherCelllndicator isset to zero in received RAR or not in operation 850 and the UE shallconsider this Random Access Response reception successful in operation880 if the OtherCelllndicator is set to zero. If the UE identifies thatit has transmitted random access preamble on other cell, then the UEidentifies whether the OtherCelllndicator is set to one in received RARin step 840. If the OtherCelllndicator is set to one, the UE identifieswhether UE's C-RNTI matches with C-RNTI received in RAR in operation870. If the UE's C-RNTI matches with the received C-RNTI, the UE shallconsider this RAR reception is successful in operation 880. If the UE'sC-RNTI does not match with the received C-RNTI, the UE shall continuemonitoring for RAR until the end of RAR window in operation 820. In theoperation 840 if the UE identifies that the OtherCelllndicator is notset to one, the UE continues monitoring for RAR until the end of the RARwindow in operation 860. In the operation 850 if the UE identifies thatthe OtherCelllndicator is not set to zero, the UE continues monitoringfor RAR until the end of the RAR window in operation 860.

FIG. 9 illustrates a method by a UE to determine successfully receivinga RAR corresponding to a PRACH preamble that is transmitted by the UEaccording to an embodiment of the disclosure.

Referring to FIG. 9 , when a downlink assignment has been received onthe NR-PDCCH for the RA-RNTI and the received TB is successfully decodedin operation 900, the UE identifies whether the RAR contains RAPIDcorresponding to the transmitted random access preamble or not inoperation 910. If the Random Access Response contains a Random AccessPreamble identifier corresponding to the transmitted Random AccessPreamble, the UE identifies whether the UE has transmitted random accesspreamble on PCell or PSCell in operation 930. If the received RAR doesnot contain RAPID corresponding to the transmitted random accesspreamble, the UE shall continue monitoring for RAR until the end of RARwindow in operation 920.

If the UE has transmitted random access preamble on PCell or PSCell, theUE identifies whether OtherCelllndicator is set to zero in received RARor not in operation 850 and the UE shall consider this Random AccessResponse reception successful in operation 970 if the OtherCelllndicatoris set to zero. If the UE identifies that it has not transmitted randomaccess preamble on PCell or PSCell, then the UE identifies whether theOtherCelllndicator is set to one in received RAR in operation 940. Ifthe OtherCelllndicator is set to one, the UE identifies whether UE'sC-RNTI matches with C-RNTI received in RAR in operation 970. If the UE'sC-RNTI matches with the received C-RNTI, the UE shall consider this RARreception is successful in operation 980. If the UE's C-RNTI does notmatch with the received C-RNTI, the UE shall continue monitoring for RARuntil the end of RAR window in operation 920. In the operation 940 ifthe UE identifies that the OtherCelllndicator is not set to one, the UEcontinues monitoring for RAR until the end of the RAR window inoperation 960. In the operation 950 if the UE identifies that theOtherCelllndicator is not set to zero, the UE continues monitoring forRAR until the end of the RAR window in operation 960.

Method 3

In this method, it is proposed that in addition to RAPID and RA-RNTIchecking, UE which has transmitted RACH preamble on another cell, alsochecks for its C-RNTI in RAR. If cell is transmitting RAR for a RACHpreamble (or MSG 1) received on another cell then it also includes UE'sC-RNTI in RAR. Since the RAR for RACH preamble (or MSG 1) received onanother cell is allowed only in case of contention free RACH, networkknows the C-RNTI of UE which has transmitted the RACH preamble.

FIGS. 10A and 10B illustrate example methods of receiving RARs accordingto various embodiments of the disclosure.

Referring to FIG. 10A, a UE 1000 transmits RACH preamble to cell 1 1010in operation 1030. Cell 1 1010 transmits the RAR corresponding to RACHpreamble received from the UE 1000 in operation 1035. In case ofcontention based RACH temporary C-RNTI is included in RAR. In case ofcontention free RACH, UE's C-RNTI may not be included in this case.Therefore, in operation 1040, the UE 1000 can determine the RAR isreceived successfully if the RAR corresponds UE's RA-RNTI, RAPID.

Referring to FIG. 10B, a UE 1000 transmits RACH preamble to cell 2 1020in operation 1050. Cell 1 1055 transmits the RAR corresponding to RACHpreamble received from the UE 1000 on cell 1 in operation 1055. Oneexample of this scenario is the carrier aggregation, where the UE 1000is configured with Cell 2 1020 as SCell and Cell 1 1010 as PCell. Inthis case, RACH preamble is transmitted on SCell and the correspondingRAR is received by UE from PCell. Cell 1 1010 also includes UE's C-RNTIin RAR. RACH preamble and/or RACH resource on which RACH preamble isreceived by Cell 2 1020 is assigned to UE, so UE's C-RNTI is known tonetwork (or gNB or cell 2). Therefore, the UE 1000 can determine the RARis received successfully if the RAR corresponds UE's RA-RNTI, RAPID,OtherCelllndicator set to 1 and received C-RNTI which matches with UE'sC-RNTI in operation 1060.

FIG. 11 illustrates a method by a UE to determine successfully receivinga RAR corresponding to a PRACH preamble that is transmitted by the UEaccording to an embodiment of the disclosure.

Referring to FIG. 11 , when a downlink assignment has been received onthe NR-PDCCH for the RA-RNTI and the received TB is successfully decodedin operation 1100, a UE identifies whether the RAR contains RAPIDcorresponding to the transmitted random access preamble or not inoperation 1110. If the Random Access Response contains a Random AccessPreamble identifier corresponding to the transmitted Random AccessPreamble, the UE identifies whether the UE has transmitted random accesspreamble on the cell from which UE has received this RAR in operation1130. If the received RAR does not contain RAPID corresponding to thetransmitted random access preamble, the UE shall continue monitoring forRAR until the end of RAR window in step 1120.

After operation 1130, the UE shall consider this Random Access Responsereception successful if the UE has transmitted random access preamble onthe cell from which RAR is received. If the UE has transmitted randomaccess preamble on the cell other than the cell from which UE hasreceived this RAR, the UE identifies whether UE's C-RNTI matches withC-RNTI in RAR in operation 1140. If UE's C-RNTI matches with C-RNTIreceived in RAR, the UE shall consider this Random Access Responsereception successful in operation 1150. If UE's C-RNTI does not matchwith C-RNTI received in RAR the UE shall continue monitoring for RARuntil the end of RAR window in operation 1120.

FIG. 12 illustrates a method by a UE to determine successfully receivinga RAR corresponding to PRACH preamble transmitted by the UE according toan embodiment of the disclosure.

Referring to FIG. 12 , when a downlink assignment has been received onthe NR-PDCCH for the RA-RNTI and the received TB is successfully decodedin operation 1200, a UE identifies whether the RAR contains RAPIDcorresponding to the transmitted random access preamble or not inoperation 1210. If the Random Access Response contains a Random AccessPreamble identifier corresponding to the transmitted Random AccessPreamble, the UE identifies whether the UE has transmitted random accesspreamble on PCell or PSCell in operation 1130. If the received RAR doesnot contain RAPID corresponding to the transmitted random accesspreamble, the UE shall continue monitoring for RAR until the end of RARwindow in operation 1220.

After operation 1230 the UE shall consider this Random Access Responsereception successful if the UE has transmitted random access preamble onPCell or PSCell. If UE has transmitted random access preamble on SCellother than PSCell or PCell, the UE identifies whether UE's C-RNTImatches with C-RNTI in RAR in operation 1240. If UE's C-RNTI matcheswith C-RNTI received in RAR, the UE shall consider this Random AccessResponse reception successful in operation 1250. If UE's C-RNTI does notmatch with C-RNTI received in RAR the UE shall continue monitoring forRAR until the end of RAR window in operation 1220.

Method 4

In this method, it is proposed that in addition to RAPID and RA-RNTIchecking, UE which performs CFRA also checks for its C-RNTI in RAR. Ifcell is transmitting RAR for a RACH preamble (or MSG 1) which wasdedicatedly assigned to UE then it also includes UE's C-RNTI in RAR.

FIGS. 13A and 13B illustrate example methods of receiving RARs accordingto various embodiments of the disclosure.

Referring to FIG. 13A, a UE 1300 transmits RACH preamble to cell 1 1310in operation 1330. Cell 1 1310 transmits the RAR corresponding to RACHpreamble received from the UE 1300 in operation 1335. In case ofcontention based RACH temporary C-RNTI is included in RAR. In case ofcontention free RACH, UE's C-RNTI is included. In operation 1340, the UE1300 determines the RAR is received successfully if the RAR correspondsto UE's RA-RNTI, RAPID in case of CBRA. The UE 1300 also determines theRAR is received successfully if the RAR corresponds to UE's RA-RNTI,RAPID and received C-RNTI which matches with UE's C-RNTI in case ofCFRA.

Referring to FIG. 13B, a UE 1300 transmits RACH preamble to cell 1320 inoperation 1350. Cell 1 1310 transmits the RAR corresponding to RACHpreamble received from the UE 1300 on cell 1 1310 in operation 1355. Oneexample of this scenario is the carrier aggregation, where the UE 1300is configured with Cell 2 1320 as S Cell and Cell 1 1310 as PCell. Inthis case, RACH preamble is transmitted on SCell and the correspondingRAR is received by UE from PCell. Cell 1 1310 also includes UE's C-RNTIin RAR. RACH preamble and/or RACH resource on which RACH preamble isreceived by Cell 2 is assigned to UE, so UE's C-RNTI is known to network(or gNB or cell 2). Therefore, the UE 1300 can determine the RAR isreceived successfully if the RAR corresponds UE's RA-RNTI, RAPID andreceived C-RNTI which matches with UE's C-RNTI in operation 1360.

FIG. 14A illustrates a method by a UE to determine successfullyreceiving a RAR corresponding to a PRACH preamble that is transmitted bythe UE according to an embodiment of the disclosure.

Referring to FIG. 14A, when a downlink assignment has been received onthe NR-PDCCH for the RA-RNTI and the received TB is successfully decodedin operation 1400, a UE identifies whether the RAR contains RAPIDcorresponding to the transmitted random access preamble or not inoperation 1405. If the Random Access Response contains a Random AccessPreamble identifier corresponding to the transmitted Random AccessPreamble, the UE identifies whether the UE has transmitted random accesspreamble using assigned preamble and/or RACH resource in operation 1415.If the received RAR does not contain RAPID corresponding to thetransmitted random access preamble, the UE shall continue monitoring forRAR until the end of RAR window in operation 1410. If the UE has nottransmitted random access preamble using assigned preamble and/or RACHresource, the UE shall consider this Random Access Response receptionsuccessful in operation 1425.

After operation 1415 if the UE has transmitted random access preambleusing assigned preamble and/or RACH resource, the UE identifies thatUE's C-RNTI matches with C-RNTI received in RAR in operation 1420. IfUE's C-RNTI matches with C-RNTI received in RAR, the UE shall considerthis Random Access Response reception successful in 1425. If UE's C-RNTIdoes not match with C-RNTI received in RAR, the UE shall continuemonitoring for RAR until the end of RAR window in operation 1410.

Method 5

In this method, it is proposed a UE which performs CFRA considers RAR issuccessfully received if PDCCH is addressed to its C-RNTI and decoded TBincludes RAR. If cell is transmitting RAR for a RACH preamble (or MSG 1)which was dedicatedly assigned to UE then it transmits PDCCH addressedto UE's C-RNTI and including RAR in the corresponding TB.

FIG. 14B illustrates a method by a UE to determine successfullyreceiving a RAR corresponding to a PRACH preamble that is transmitted bythe UE according to an embodiment of the disclosure.

Referring to FIG. 14B, in operation 1430, a UE identifies that the UEhas transmitted random access preamble using assigned preamble and/orRACH resource. If the UE has transmitted random access preamble usingassigned preamble and/or RACH resource, the UE identifies that adownlink assignment has been received on the NR-PDCCH for the C-RNTI andthe received TB is successfully decoded in operation 1440. If the UE didnot transmit random access preamble using assigned preamble and/or RACHresource, the UE identifies that a downlink assignment has been receivedon the NR-PDCCH for the RA-RNTI and the received TB is successfullydecoded in operation 1435.

If the downlink assignment was not received on the NR-PDCCH for theRA-RNTI and the received TB is successfully decoded in operation 1435,the UE shall continue monitoring for RAR until the end of RAR window inoperation 1465. If a downlink assignment has been received on theNR-PDCCH for the RA-RNTI and the received TB is successfully decoded,the UE identifies whether RAR contains RAPID of transmitted RA preamblein operation 1450. If the RAR contains corresponding RAPID, the UE shallconsider the RAR reception successful in 1470. If RAR does not containcorresponding RAPID, the UE shall continue monitoring for RAR until theend of RAR window in operation 1465.

If the downlink assignment has been received on the NR-PDCCH for theC-RNTI and the received TB is successfully decoded in operation 1440,the UE identifies whether MAC packet data unit (PDU) in the TB containsRAR in operation 1455. If the downlink assignment was not received onthe NR-PDCCH for the C-RNTI, the UE shall continue monitoring for RARuntil the end of RAR window in operation 1465. If the MAC PDU in the TBcontains the RAR the UE shall consider the RAR reception successful in1470. If the MAC PDU in the TB does not contain the RAR the UE shallcontinue monitoring for RAR until the end of RAR window in operation1465.

In an embodiment, it is proposed that a UE which performs CFRA considersRAR is successfully received if it receives PDCCH addressed to itsC-RNTI after transmitting PRACH preamble. The PDCCH may indicate DL orUL assignment.

RAR MAC PDU Design

The gNB transmits RAR MAC PDU in response to PRACH preamble(s) receivedfrom one or more UE(s).

RAR MAC PDU Design 1

FIG. 15 illustrates a RAR MAC PDU structure according to an embodimentof the disclosure.

Referring to FIG. 15 , a RAR MAC PDU consists of a MAC header 1500 andzero or more MAC Random Access Responses (MAC RAR) and optionallypadding. The MAC header is of variable size. A MAC PDU header consistsof one or more MAC PDU subheaders; each subheader corresponding to a MACRAR 1540 except for the Backoff Indicator subheader 1510 and systeminformation (SI) request acknowledgement (ACK) subheader 1520. In anembodiment, a Backoff Indicator subheader and SI request ACK subheader,if included, may be included in beginning of MAC PDU Header. In anembodiment, SI request ACK subheader may not be there. In an embodimentthere can be more than one SI request ACK subheader.

A MAC PDU subheader corresponding to MAC RAR 1530 consists of at leastthree header fields E (extension)/T (Type)/RAPID (random access preambleidentifier). Reserved fields may be included to octet align the MACsubheader. This can also be referred as RAR subheader which have acorresponding MAC RAR.

A Backoff Indicator subheader 1510 consists of at least three fields E(extension)/T (type)/BI (backoff indicator). Reserved fields may beincluded to octet align Backoff Indicator subheader. There is no MAC RARcorresponding to this subheader.

A SI request ACK subheader 1520 consists of at least three fieldsE/T/RAPID (random access preamble identifier). Reserved fields may beincluded to octet align SI request ACK subheader. There is no MAC RARcorresponding to this subheader. This can also be referred as RARsubheader which does not have a corresponding MAC RAR. SI request ACKsubheader and MAC RAR subheader has same fields. Hence they can both bereferred as RAR subheader.

The subheader corresponding to MAC RAR 1530 and SI request subheader1520 has same fields. So some mechanism is needed for receiver todistinguish them.

In an embodiment, type field in MAC subheader can indicate whether MACsubheader is a backoff indicator (or information) subheader i.e. itincludes a backoff indicator (BI) (or information) or MAC subheader is aSI request ACK subheader including RAPID or MAC subheader includes RAPIDand corresponds to a MAC RAR. Distinct value of type field ‘T’ are usedto indicate backoff indicator subheader, SI request ACK subheader andMAC RAR subheader. An example setting of type field ‘T’ is shown below.

-   -   T=01 (in binary) may indicate that MAC subheader is backoff        indicator (or information) subheader    -   T=10 (in binary) may indicates MAC subheader is SI request ACK        subheader or RAR subheader which does not have a corresponding        MAC RAR    -   T=11 (in binary) may indicates MAC subheader is MAC RAR        subheader or RAR subheader which have a corresponding MAC RAR

In another embodiment, the Type field in MAC subheader only indicateswhether the MAC subheader contains a Random Access preamble identifier(ID) or a BI (or information). If the type field indicates that MACsubheader contains a Random Access preamble ID, then UE checks if theRAPID is equal to RAPID of one of random access preambles reserved forSI request. If the RAPID in MAC subheader is equal to RAPID of one ofrandom access preambles reserved for SI request, then this MAC subheaderis the MAC subheader for SI request ACK and there is no MAC RARcorresponding to it. Otherwise, this MAC subheader is the MAC subheaderfor RAR and there is a MAC RAR corresponding to it.

Alternatively, a UE checks if the RAPID is equal to RAPID of one ofrandom access preambles reserved for RA (both contention free andcontention based) procedure excluding SI request procedure. If the RAPIDin MAC subheader is equal to RAPID of random access preambles reservedfor RA (both contention free and contention based) procedure excludingSI request procedure, then this MAC subheader is the MAC subheader forRAR and there is a MAC RAR corresponding to it. Otherwise, this MACsubheader is for SI request ACK and there is no MAC RAR corresponding toit. UE can obtain the information about the random access preamblesreserved for RA (both contention free and contention based) procedureexcluding SI request procedure from system information (e.g. systeminformation block 1 (SIB1)) transmitted by gNB. For example, GNB canbroadcast a parameter TotalNumberOfRAPreambles in system information.Preambles with RAPID less than the TotalNumberOfRAPreambles are used forRA (both contention free and contention based) procedure excluding SIrequest procedure. In another example where gNB broadcasts multiplesynchronization signal (SS) blocks (SSBs), GNB can broadcast a parameterTotalNumberOfRAPreamblesPerSSB in system information. If the number (N,signaled by network) of SSBs per PRACH transmission occasion is greaterthan 1, for the ith (i=0 to N−1) SSB mapped to a PRACH transmissionoccasion, preambles from i*(64/N) to[i*(64/N)+TotalNumberOfRAPreamblesPerSSB−1] are used for RA procedureexcluding SI request procedure. For example if 2 SSBs are mapped to aPRACH transmission occasion and TotalNumberOfRAPreamblesPerSSB is set to24, then preambles 0 to 23 and 32 to 55 are for RA procedure excludingSI request procedure. If the number (N) of SSBs per PRACH transmissionoccasion is preambles from 0 to [TotalNumberOfRAPreamblesPerSSB−1] areused for RA procedure excluding SI request procedure. So UE can know allpreambles used for RA procedure excluding SI request procedure. UE canalso obtain the information about the random access preambles reservedfor SI request procedure from system information (e.g. SIB1) transmittedby gNB.

In another embodiment, the Type field only indicates whether the MACsubheader contains a Random Access preamble ID or a Backoff Indicator(or information). If the type field indicates that MAC subheadercontains a Random Access preamble ID, then UE checks if the RA-RNTI isequal to RA-RNTI reserved for SI request ACK or is equal to RA-RNTIcorresponding to RACH resource reserved for SI request. If yes, thenthis MAC subheader is the MAC subheader for SI request ACK and there isno MAC RAR corresponding to it. Otherwise, this MAC subheader is the MACsubheader for RAR and there is a MAC RAR corresponding to it.

FIGS. 16A and 16B illustrate various embodiments of a type field in aMAC subheader according to various embodiments of the disclosure.

Referring to FIGS. 16A and 16B, the Type (T1) field 1600 only indicateswhether the MAC subheader contains a Random Access preamble ID or a BI.If the T1 field 1600 indicates that MAC subheader contains a RandomAccess preamble identifier, then another type (T2) field 1610 indicateswhether this MAC subheader has a corresponding MAC RAR or not. In otherwords, if the T1 field (T1) 1600 indicates that MAC subheader contains aRandom Access preamble ID, then T2 field 1610 indicates whether this MACsubheader is a SI request ACK subheader or is a MAC RAR subheader. TheT2 field 1610 is included only when the T1 field 1600 indicates RAPID isincluded in MAC subheader. So the T2 field 1610 is included only in SIrequest ACK subheader and RAR subheader. Extension flag E in subheaderindicates whether this is the last subheader in MAC header or not. R isthe reserved field.

RAR MAC PDU Design 2

FIG. 17A illustrates another RAR MAC PDU structure according to anembodiment of the disclosure.

Referring to FIG. 17 , a RAR MAC PDU 1700 consists of one or more MACsub headers and zero or more MAC Random Access Responses (MAC RAR) andoptionally padding. MAC RAR subheader is present before each MAC RARincluded in MAC PDU. In an embodiment, BI subheader 1710 and SIsubheader 1720 if present may be included in beginning of MAC PDU. Thereis no MAC RAR corresponding to BI subheader and SI subheader. In anembodiment there can be more than one SI request ACK subheader in MACPDU.

FIG. 17B illustrates another RAR MAC PDU structure according to anembodiment of the disclosure.

Referring to FIG. 17B, a MAC PDU consists of one or more MAC sub-PDUs1730 and optional padding 1735. Each MAC sub-PDU consists one of thefollowing:

-   -   a MAC subheader only    -   a MAC subheader with backoff indicator only OR a MAC subheader        with RAPID only (i.e. acknowledgement for SI request)    -   a MAC subheader with RAPID and MAC RAR

A MAC sub-PDU with backoff information if present in the RAR MAC PDU isincluded at the beginning of the RAR MAC PDU. A MAC sub-PDU(s) for SIrequest acknowledgement if present in the RAR MAC PDU can be includedanywhere in the RAR MAC PDU. In an embodiment, MAC sub-PDU(s) for SIrequest acknowledgement if present in the RAR MAC PDU can be included atthe end of the RAR MAC PDU to facilitate quick processing of MAC sub-PDUwith RAR.

In an embodiment, a MAC PDU subheader corresponding to MAC RAR consistsof at least three header fields E/T/RAPID. The Extension field ‘E’ is aflag indicating if the MAC sub-PDU including this MAC subheader is thelast MAC sub-PDU or not in the MAC PDU. The E field is set to “1” toindicate at least another MAC sub-PDU follows. The E field is set to “0”to indicate that the MAC sub-PDU including this MAC subheader is thelast MAC sub-PDU in the MAC PDU. In an alternate embodiment, a MAC PDUsubheader corresponding to MAC RAR consists of at least two headerfields T/RAPID. Reserved fields may be included to octet align the MACsubheader. This can also be referred as RAR subheader which have acorresponding MAC RAR. MAC RAR subheader in MAC sub-PDU is followed byMAC RAR.

In an embodiment, a Backoff Indicator (or information) subheaderconsists of at least three fields E/T/BI. The Extension field ‘E’ is aflag indicating if the MAC sub-PDU including this MAC subheader is thelast MAC sub-PDU or not in the MAC PDU. The E field is set to “1” toindicate at least another MAC sub-PDU follows. The E field is set to “0”to indicate that the MAC sub-PDU including this MAC subheader is thelast MAC sub-PDU in the MAC PDU. In an alternate embodiment, a BackoffIndicator (or information) subheader consists of at least two fieldsT/BI. Reserved fields may be included to octet align Backoff Indicator(or information) subheader. There is no MAC RAR corresponding to thissubheader. MAC sub-PDU carrying back information consists of onlybackoff indicator (or information) subheader. Backoff indicator (orinformation) subheader in MAC sub-PDU is not followed by MAC RAR.

In an embodiment, a SI request ACK subheader consists of at least threefields E/T/RAPID. The Extension field ‘E’ is a flag indicating if theMAC sub-PDU including this MAC subheader is the last MAC sub-PDU or notin the MAC PDU. The E field is set to “1” to indicate at least anotherMAC sub-PDU follows. The E field is set to “0” to indicate that the MACsub-PDU including this MAC subheader is the last MAC sub-PDU in the MACPDU. In an alternate embodiment, an SI request ACK subheader consists ofat least two fields T/RAPID. Reserved fields may be included to octetalign SI request ACK subheader. There is no MAC RAR corresponding tothis subheader. This can also be referred as RAR subheader which doesnot have a corresponding MAC RAR. MAC sub-PDU carrying SI request ACKconsists of only SI request ACK subheader. SI request ACK subheader inMAC sub-PDU is not followed by MAC RAR.

The subheader corresponding to MAC RAR and SI request subheader has samefields. So some mechanism is needed for receiver to distinguish them.

In an embodiment, type field in MAC subheader can indicate whether MACsubheader (i.e. BI subheader) includes backoff indicator (orinformation) or MAC subheader (i.e. SI request ACK subheader) includesRAPID and is not followed by MAC RAR or MAC subheader includes RAPID andis followed by MAC RAR. An example setting of type field is shown below.

-   -   T=01 (in binary) or 1 in decimal may indicate MAC subheader        (i.e. backoff indicator (or information) subheader) includes        indicator (or information)    -   T=10 (in binary) or 2 in decimal may indicate MAC subheader        (i.e. SI request ACK subheader) includes RAPID and is not        followed by MAC RAR    -   T=11 (in binary) or 3 may indicate MAC subheader includes RAPID        and is followed by MAC RAR

In another embodiment, the Type field in MAC subheader indicates whetherthe MAC subheader contains a Random Access preamble identifier or aBackoff Indicator (or information). If the type field in MAC subheaderindicates random access preamble ID, then UE checks if the RAPID isequal to RAPID of one of random access preambles reserved for SIrequest. If the RAPID in MAC subheader is equal to RAPID of one ofrandom access preambles reserved for SI request, then this MAC subheaderis the MAC subheader for SI request ACK and there is no MAC RARcorresponding to it. Otherwise, this MAC subheader is the MAC subheaderfor RAR and there is a MAC RAR corresponding to it.

Alternately, the UE checks if the RAPID is equal to RAPID of one ofrandom access preambles reserved for RA (both contention free andcontention based) procedure excluding SI request procedure. If the RAPIDin MAC subheader is equal to RAPID of random access preambles reservedfor RA (both contention free and contention based) procedure excludingSI request procedure, then this MAC subheader is the MAC subheader forRAR and there is a MAC RAR corresponding to it. Otherwise, this MACsubheader is for SI request ACK and there is no MAC RAR corresponding toit. UE can obtain the information about the random access preamblesreserved for RA (both contention free and contention based) procedureexcluding SI request procedure from system information (e.g. SIB1)transmitted by gNB. For example, GNB can broadcast a parameterTotalNumberOfRAPreambles in system information. Preambles withRAPID<TotalNumberOfRAPreambles are used for RA (both contention free andcontention based) procedure excluding SI request procedure. In anotherexample where gNB broadcasts multiple SSBs, GNB can broadcast aparameter TotalNumberOfRAPreamblesPerSSB in system information. If thenumber (N, signaled by network) of SSBs per PRACH transmission occasionis greater than 1, for the ith (i=0 to N−1) SSB mapped to a PRACHtransmission occasion, preambles from i*(64/N) to[i*(64/N)+TotalNumberOfRAPreamblesPerSSB−1] are used for RA procedureexcluding SI request procedure. For example if 2 SSBs are mapped to aPRACH transmission occasion and TotalNumberOfRAPreamblesPerSSB is set to24, then preambles 0 to 23 and 32 to 55 are for RA procedure excludingSI request procedure. If the number (N) of SSBs per PRACH transmissionoccasion is preambles from 0 to [TotalNumberOfRAPreamblesPerSSB−1] areused for RA procedure excluding SI request procedure. So UE can know allpreambles used for RA procedure excluding SI request procedure. UE canalso obtain the information about the random access preambles reservedfor SI request procedure from system information (e.g. SIB1) transmittedby gNB.

In another embodiment, the Type field in MAC subheader indicates whetherthe MAC subheader contains a Random Access preamble ID or a BackoffIndicator (or information). If the type field in MAC subheader indicatesrandom access preamble ID, then UE checks if the RA-RNTI is equal toRA-RNTI reserved for SI request ACK or is equal to RA-RNTI correspondingto RACH resource reserved for SI request. If yes, then this MACsubheader is the MAC subheader for SI request ACK and there is no MACRAR corresponding to it. Otherwise, this MAC subheader is the MACsubheader for RAR and there is a MAC RAR corresponding to it.

In another embodiment, the Type (T1) field only indicates whether theMAC subheader contains a Random Access preamble ID or a BackoffIndicator (or information). If the type field (T1) indicates that MACsubheader contains a Random Access preamble ID, then another type fieldT2 indicates whether this MAC subheader has a corresponding MAC RAR ornot. If the type field (T1) indicates that MAC subheader contains aRandom Access preamble ID, then another type field T2 indicates whetherthis MAC subheader is for SI request ACK or is a MAC RAR subheader. T2field is included only when T1 field indicates RAPID is included in MACsubheader.

FIG. 17C illustrates a type field in a MAC subheader according to anembodiment of the disclosure.

Referring to FIG. 17C, a type field T or type field T1 can also indicatepadding (or padding starts at the next byte). For example T or T1 inabove embodiments can be set to zero to indicate padding or paddingsubheader 1740. In this case extension field E is not required in MACsubheader. In an alternate embodiment UE can check the whether the bytewhich it has to process for MAC subheader is zero or not. If zero,padding is there including this byte. If not zero, MAC subheader ispresent and UE parses the fields of MAC subheader. In an alternateembodiment UE check whether the first byte (or all bytes) of MACsubheader is zero or not. If zero, padding is there. If not zero, MACsubheader is present and UE parses the fields of MAC subheader.

In an embodiment, ‘E’ field is included in MAC subheader, The Extensionfield ‘E’ is a flag indicating if the MAC sub-PDU including this MACsubheader is the last MAC sub-PDU or not in the MAC PDU. The E field isset to “1” to indicate at least another MAC sub-PDU follows. The E fieldis set to “0” to indicate that the MAC sub-PDU including this MACsubheader is the last MAC sub-PDU in the MAC PDU. Anything left in theRAR MAC PDU after the last MAC sub-PDU is padding.

RAR MAC PDU Design 3

FIG. 18 illustrates another RAR MAC PDU structure according to anembodiment of the disclosure.

Referring to FIG. 18 , a RAR MAC PDU consists of one or more MAC subheaders and zero or more MAC Random Access Responses (MAC RAR) andoptionally padding. MAC RAR subheader 1810 is present before each MACRAR 1820 included in MAC PDU. In an embodiment, BI subheader 1800 ifpresent may be included in beginning of MAC PDU. There is no MAC RARcorresponding to BI subheader.

A MAC PDU subheader corresponding to MAC RAR consists of at least threeheader fields E/T/RAPID. In an alternate embodiment, a MAC PDU subheadercorresponding to MAC RAR consists of at least two header fields T/RAPID.Reserved fields may be included to octet align the MAC subheader.

A Backoff Indicator subheader consists of at least three fields E/T/BI.In an alternate embodiment, a Backoff Indicator (or information)subheader consists of at least two fields T/BI. Reserved fields may beincluded to octet align Backoff Indicator subheader. There is no MAC RARcorresponding to this subheader.

In an embodiment type field T can indicate padding (or padding starts atthe next byte). For example type field T in above embodiments can be setto zero to indicate padding or padding subheader. In an alternateembodiment UE can check the whether the byte which it has to process forMAC subheader is zero or not. If zero, padding is there including thisbyte. If not zero, MAC subheader is present and UE parses the fields ofMAC subheader. In an alternate embodiment UE check whether the firstbyte (or all bytes) of MAC subheader is zero or not. If zero, padding isthere. If not zero, MAC subheader is present and UE parses the fields ofMAC subheader.

MAC RAR Design MAC RAR Design 1

MAC RAR comprises of timing advance command, UL grant and C-RNTI fields.Reserved fields may be included to octet align MAC RAR. In certainscenarios, some fields such as UL grant and/or C-RNTI may not bepresent. A type or format field may be included in MAC RAR. The type orformat field indicates whether UL grant and/or C-RNTI is present in MACRAR or not. In alternate embodiment, type or format field indicateswhich of timing advance command, UL grant and C-RNTI is present in MACRAR. In an alternative embodiment type or format field may indicate oneof the following:

-   -   MAC RAR includes timing advance command, UL grant and C-RNTI    -   MAC RAR includes timing advance command and UL grant    -   MAC RAR includes only timing advance command    -   MAC RAR includes timing advance command and C-RNTI

It is to be noted that in a system some of the above combinations or allof the above combinations may be indicated using type or format field.Each of the above can be defined as different MAC RAR format. The typeof format field is present in each MAC RAR format at same location. Thetype of format field indicates MAC RAR format type. For example,

-   -   type or format field=01 can mean MAC RAR includes timing advance        command, UL grant and C-RNTI    -   type or format field=10 can mean MAC RAR includes timing advance        command and UL grant    -   type or format field=11 can mean MAC RAR includes only timing        advance command

Based on type or format field, since UE knows the content of MAC RAR, italso can know the length of MAC RAR as size of each field ispre-defined. In an alternate embodiment, the type/format field toindicate MAC RAR content or format, may be included in MAC subheader.

MAC RAR Design 2

MAC RAR comprises of timing advance command, UL grant and C-RNTI/SI ACKInfo fields. Reserved fields may be included to octet align MAC RAR. Incertain scenarios, some fields such as UL grant and/or C-RNTI and/or SIACK Info may not be present. A type or format field may be included inMAC RAR. The type or format field indicates whether UL grant and/orC-RNTI and/or SI ACK Info is present in MAC RAR or not. In alternateembodiment, type or format field indicates which of timing advancecommand, UL grant, C-RNTI and SI ACK info is present in MAC RAR. In analternate embodiment type or format field may indicate one of thefollowing:

-   -   MAC RAR includes timing advance command, UL grant and C-RNTI    -   MAC RAR includes timing advance command and UL grant    -   MAC RAR includes only timing advance command    -   MAC RAR includes only SI ACK info

It is to be noted that in a system some of the above combinations or allof the above combinations may be indicated using type or format field.Each of the above can be defined as different MAC RAR format. The typeof format field is present in each MAC RAR format at same location. Thetype of format field indicates MAC RAR format type. For example,

-   -   type or format field=01 can mean MAC RAR includes timing advance        command, UL grant and C-RNTI    -   type or format field=10 can mean MAC RAR includes timing advance        command and UL grant    -   type or format field=11 can mean MAC RAR includes only timing        advance command    -   type or format field=00 means MAC RAR includes only SI ACK info

Based on type or format field, since UE knows the content of MAC RAR, italso can know the length of MAC RAR as size of each field ispre-defined. In an alternate embodiment, the type/format field toindicate MAR RAR content or format, may be included in MAC subheader.

MAC RAR Design 3

MAC RAR comprises of timing advance command, UL grant, C-RNTI and SI ACKInfo fields. Reserved fields may be included to octet align MAC RAR. Incertain scenarios, some fields such as SI ACK Info may not be present. Atype or format field may be included in MAC RAR. The type or formatfield indicates whether SI ACK Info is present in MAC RAR or not. In analternative embodiment type or format field may indicate one of thefollowing:

-   -   MAC RAR includes timing advance command, UL grant and C-RNTI    -   MAC RAR includes only SI ACK info

Each of the above can be defined as different MAC RAR format. The typeof format field is present in each MAC RAR format at same location. Thetype of format field indicates MAC RAR format type. For example,

-   -   type or format field=0 can mean MAC RAR includes timing advance        command, UL grant and C-RNTI    -   type or format field=1 can mean MAC RAR includes only SI ACK        info

Based on type or format field, since UE knows the content of MAC RAR, italso can know the length of MAC RAR as size of each field ispre-defined. In an alternate embodiment, the type/format field toindicate MAR RAR content or format, may be included in MAC subheader.

PRACH Transmission Counting

During the random access procedure UE maintains a transmission counterto count the number of PRACH preamble transmissions. The firstembodiment for PRACH transmission counting is using Two Counters.

In this approach two counters PREAMBLE_TRANSMISSION_COUNTER andPREAMBLE_POWER_RAMPING_COUNTER can be defined in MAC specification. ThePREAMBLE_TRANSMISSION_COUNTER is used to count the number of PRACHtransmissions during a random access procedure and to take appropriateactions when the count reaches the maximum value.PREAMBLE_POWER_RAMPING_COUNTER is used in calculating power for PRACH(re-) transmissions. The MAC entity actions for these counters are asfollows:

-   -   MAC entity initializes PREAMBLE_TRANSMISSION_COUNTER and        PREAMBLE_POWER_RAMPING_COUNTER to 1 when the Random procedure is        initiated.    -   If RAR reception is not successful or contention resolution is        not successful the MAC entity shall:    -   increments PREAMBLE_TRANSMISSION_COUNTER by 1;    -   increments PREAMBLE_POWER_RAMPING_COUNTER by 1 if UE does not        change its beam (or UL transmission (TX) beam) and SS block        during PRACH retransmission. OR if beam (or UL TX beam) and SS        block for next PRACH transmission is same as previous PRACH        transmission, increment PREAMBLE_POWER_RAMPING_COUNTER by 1

In an alternate embodiment, PHY layer may send a notification to MAClayer indicating it to not ramp up power for next PRACH transmission.PHY layer may send this notification if the UL TX beam and/or SS blockis changed i.e. if the UL TX beam and/or SS block for next PRACHtransmission is different from beam used in previous PRACH transmission.If RAR reception is not successful or contention resolution is notsuccessful, MAC entity shall perform the following operation.

-   -   if MAC layer has received the notification from PHY layer to not        ramp up power it shall not increment        PREAMBLE_POWER_RAMPING_COUNTER by 1. Otherwise it shall        increment PREAMBLE_POWER_RAMPING_COUNTER by 1.

In an alternate embodiment, PHY layer may send a notification i.e. powerramping suspension notification to MAC layer in case UL TX beam forPRACH retransmission is changed. If RAR reception is not successful orcontention resolution is not successful, MAC entity shall perform thefollowing operation.

-   -   if RAR reception is not successful or contention resolution is        not successful the MAC entity shall:    -   increments PREAMBLE_TRANSMISSION_COUNTER by 1;    -   if MAC layer has not received the notification for suspending        the power ramping and SS block selected for PRACH retransmission        is not changed it shall increment PREAMBLE_POWER_RAMPING_COUNTER        by 1. Otherwise it shall not increment        PREAMBLE_POWER_RAMPING_COUNTER by 1.

In an alternate embodiment, PHY layer may send a notification i.e. powerramping suspension notification to MAC layer in case UL TX beam forPRACH retransmission is changed. UE performs the following operationduring preamble transmission:

-   -   if PREAMBLE_TRANSMISSION_COUNTER is greater than one and the        notification of suspending power ramping has not been received        from lower layers, and SS block selected is not changed (i.e.        same as the previous PRACH preamble transmission during the        random access procedure):    -   increment PREAMBLE_POWER_RAMPING_COUNTER by one

In an embodiment, PHY layer may send a power ramping suspensionnotification to MAC layer if L1 drops the PRACH preamble transmission ortransmit PRACH preamble by scaling down the power. The UE operationconsidering power ramping suspension notification, and SS block is asfollows.

If RAR reception is not successful or contention resolution is notsuccessful, MAC entity shall

-   -   If RAR reception is not successful or contention resolution is        not successful the MAC entity shall:    -   if MAC layer has not received the notification for suspending        the power ramping counter and SS block selected for PRACH        retransmission is not changed it shall increment        PREAMBLE_POWER_RAMPING_COUNTER by 1.

In an embodiment, PHY layer may send a power ramping suspensionnotification to MAC layer if L1 drops the PRACH preamble transmission ortransmit PRACH preamble by scaling down the power. The UE operationconsidering power ramping suspension notification and SS block is asfollows

If RAR reception is not successful or contention resolution is notsuccessful, MAC entity shall

-   -   if RAR reception is not successful or contention resolution is        not successful the MAC entity shall:    -   UE performs the following operation during preamble        transmission:    -   if PREAMBLE_TRANSMISSION_COUNTER is greater than one and the        power ramping suspension notification has not been received from        lower layers, and SS block selected is not changed (i.e. it is        same as the previous PRACH preamble transmission during the        random access procedure):    -   increment PREAMBLE_POWER_RAMPING_COUNTER by one.

The second embodiment for PRACH transmission counting is using singlecounter.

In this approach only one counter PREAMBLE_TRANSMISSION_COUNTER isdefined in MAC specification. The PREAMBLE_TRANSMISSION_COUNTER is usedto count the number of PRACH transmissions during a random accessprocedure and to take appropriate actions when the count reaches themaximum value.

PREAMBLE_POWER_RAMPING_COUNTER is also used in calculating power forPRACH (re-) transmissions. The MAC entity actions are as follows:

-   -   MAC entity initializes PREAMBLE_TRANSMISSION_COUNTER to 1 when        the Random procedure is initiated.    -   If RAR reception is not successful or contention resolution is        not successful the MAC entity shall    -   If UL TX beam is not changed increment        PREAMBLE_TRANSMISSION_COUNTER by 1 or if beam (or UL TX beam)        for next PRACH transmission is same as previous PRACH        transmission, increment PREAMBLE_TRANSMISSION_COUNTER by 1

In an alternate embodiment, PHY layer may send a notification to MAClayer if the UL TX beam for next PRACH transmission is different frombeam used in previous PRACH transmission. If RAR reception is notsuccessful or contention resolution is not successful, MAC entity shallperform the following operation:

—If MAC layer has received the notification from PHY layer it shall notincrement PREAMBLE_TRANSMISSION_COUNTER by 1. Otherwise it shallincrement PREAMBLE_TRANSMISSION_COUNTER by 1.

RA-RNTI Calculation

After transmitting the PRACH preamble, a UE monitors the PDCCH of thespecial cell (SPCell) for Random Access Response(s) identified by theRA-RNTI(s) during the RAR window. The RA-RNTI is computed as describedin further detail below.

Scenario 1: In time domain, only one PRACH transmission occasion issupported in one slot

Method 1

In an embodiment of the proposed disclosure, the RA-RNTI associated withthe PRACH in which the Random Access Preamble is transmitted, iscomputed as:

RA-RNTI=1+t_id+X*f_id  (Eq. 1)

In equation 1, t_id is an index of the first slot of the PRACHtransmission occasion (0≤t_id<X). In an embodiment, the slots in a radioframe are sequentially numbered starting from zero. Depending on thesubcarrier spacing (SCS) for Msg1 (or random access preamble)transmission, number of slots in a radio frame can vary from 10 to 80 asshown in Table 1 below. Maximum number of slots in a radio frame is 80,so X can be equal to 80 if maximum RAR window size is one radio framei.e., 10 ms.

TABLE 1 SCS for determining # of slots in # of slots in RACH slot asubframe a radio frame 15 KHz 1 10 30 KHz 2 20 60 KHz 4 40 120 KHz  8 80

Alternately, if PRACH transmission occasion can start only in some slotsin a radio frame, X can be smaller than 80. For example, if PRACHtransmission occasion can only start in slots 0, 4, 8 and 12, X can be 4as there are four possible slots where PRACH transmission occasion canstart in a radio frame. Each of these slots (0, 4, 8, 12 in the example)where PRACH transmission occasion can start are logically indexedsequentially (i.e. t_id for PRACH transmission occasion starting in slot0 is 0, t_id for PRACH transmission occasion starting in slot 4 is 1,t_id for PRACH transmission occasion starting in slot 8 is 2 and t_idfor PRACH transmission occasion starting in slot 12 is 3).

In an embodiment, X can be set to a value depending on numerology orSCS. For example for SCS of 15 KHz it can be set to 10 as there are 10slots in a radio frame in this case. For SCS of 30 KHz it can be set to20 as there 20 slots in a radio frame in this case. For SCS of 60 KHz itcan be set to 40 as there are 40 slots in a radio frame in this case.For SCS of 120 KHz it can be set to 80 as there are 80 slots in a radioframe in this case. The slots in a radio frame are sequentially numberedstarting from zero.

FIG. 19 illustrates an embodiment of indexing slots for computing aRA-RNTI according to an embodiment of the disclosure.

Referring to FIG. 19 , if maximum size of RAR window is greater than oneradio frame called N radio frames, then slots in every N consecutiveradio frames starting from radio frame with system frame number (SFN) 0,are indexed sequentially from zero. Slots in SFN 0 to SFN N−1 areindexed sequentially start from zero. Slots in SFN N to SFN 2N−1 areindexed sequentially start from zero and so on. In this case X can beequal to 80*N, as maximum number of slots in radio frame is 80 andmaximum number of slots in N radio frames is N*80. The slots are indexedsequentially for N consecutive radio frames starting from first slot ofevery radio frame with SFN which satisfies equation

FIG. 20 illustrates another embodiment of indexing slots for computing aRA-RNTI according to an embodiment of the disclosure.

Referring to FIG. 20 , if maximum size of RAR window is greater than oneradio frame called N sub frames, then slots in N consecutive sub framesstarting from 1st subframe in radio frame with SFN 0, are indexedsequentially from zero. Slots in subframe 0 to subframe N−1 are indexedsequentially start from zero. Slots in subframe N to subframe 2N−1 areindexed sequentially starting from zero and so on. In this case X can beequal to 8*N as maximum number of slots in a subframe is 8. The slotsare indexed sequentially for N subframes frames starting from first slotof every subframe ‘i’ in radio frame ‘j’ which satisfies equation(j*10+i) mod N=0, where ‘j’ is the SFN of radio frame and ‘i’ is thesubframe index (with radio frame subframes are indexed from 0 to 9sequentially) of subframe within a radio frame.

FIG. 21 illustrates another embodiment of indexing slots for computing aRA-RNTI according to an embodiment of the disclosure.

Referring to FIG. 21 , if maximum size of RAR window is N slots, thenstarting from 1st slot of SFN 0, every N consecutive slots are indexedsequentially from zero to N−1. In this case X can be equal to N.

In this example, f_id is an index of the PRACH transmission occasion, inascending order of frequency domain; 0≤f_id<Y; Y depends on number ofPRACH transmission occasions supported in frequency domain. In anembodiment, if multiple resource pools (e.g. separate resource pool forbeam failure recovery, handover, etc.) for RACH are configured,frequency division multiplexed PRACH transmission occasions in eachresource pool can be independently numbered starting from zero. Forexample, if there are two resource pools, resource pool 1 having twofrequency division multiplexed PRACH transmission occasions and resourcepool 2 having four frequency division multiplexed PRACH transmissionoccasions, the frequency division multiplexed PRACH transmissionoccasions are numbered 0 and 1 in resource pool 1 and the frequencydivision multiplexed PRACH transmission occasions are numbered 0, 1, 2,and 3 in resource pool 2.

In another embodiment, if multiple resource pools for RACH areconfigured, frequency division multiplexed PRACH transmission occasionsare numbered starting from zero across resource pools. For example, ifthere are two resource pools. In resource pool 1 there are two frequencydivision multiplexed PRACH transmission occasions. In resource pool 2there are four frequency division multiplexed PRACH transmissionoccasions. The frequency division multiplexed PRACH transmissionoccasions are numbered 0 and 1 in resource pool 1. The frequencydivision multiplexed PRACH transmission occasions are numbered 2, 3, 4,and 5. In another embodiment, if multiple resource pools for RACH areconfigured, network may configure the starting f_id to be used for eachresource pool. A frequency division multiplexed (FDMed) PRACHtransmission occasions in a resource pool are sequentially numberedstarting from f_id indicated by network for that resource pool.

In an embodiment of the proposed disclosure, the RA-RNTI associated withthe PRACH in which the Random Access Preamble is transmitted, iscomputed as:

RA-RNTI=1+t_id+X*f_id+X*Y*(SFN_id mod(Wmax/Number of slots in a radioframe))

In this example, SFN_id is the index of the first radio frame of thePRACH transmission occasion, and Wmax is maximum RAR window size inslots. t_id and f_id are as defined earlier.

There can be several ways in which RA-RNTI can be computed using t_idand f_id. The various ways of computing RA-RNTI based on t_id and f_idis as follows:

RA-RNTI=1+Parameter 1+C1*Parameter 2  (Eq. 2)

In equation 2, Parameter 1 is one of t_id or f_id, Parameter 2 is one of[{t_id, f_id}−{Selected Parameter 1}], and C1 is a number of distinctvalues of selected parameter 1.

If the selected parameter 1 is t_id, then the selected parameter 2 isf_id and C1 equals X as 0≤t_id<X. The RA-RNTI based on Eq. 2 is equal to1+t_id+C1*f_id. If the selected parameter 1 is f_id, then the selectedparameter 2 is t_id and C1 equals Y as 0≤f_id<Y. The RA-RNTI based onEq. 2 is equal to 1+f_id+C1*t_id. One of the ways of computing RA-RNTIbased on the above mechanism can be pre-defined in the system.

In another embodiment, random access preamble can be transmitted onfrequency F1 and RAR can be received on frequency F2. In this caseinformation about the carrier on which random access preamble istransmitted can also be included in RA-RNTI computation. For example,serving cell can configure a supplementary uplink (SUL) frequency calledFy. The uplink frequency of serving cell is called Fx. Serving cellconfigures PRACH resources on frequency Fy and Fx. Based on certaincriteria UE selects PRACH resource on either frequency Fy or frequencyFx for random access preamble transmission. If UE transmits randomaccess preamble on frequency Fy, it receives RAR in DL of serving cell.If the UE transmits random access preamble on frequency Fx, it receivesRAR in DL of serving cell. The RA-RNTI can be computed as follows:

RA-RNTI=1+t_id+X*f_id+X*Y*c_id  (Eq. 3)

In Equation 3, t_id, f_id, X, and Y are same as explained earlier, andc_id is set to ‘1’ if UE transmits random access preamble on SUL or elsec_id is set to ‘0.’

In an embodiment, the value of c_id to be used specific to a carrierfrequency (or specific to serving cell) on which random access preambleis transmitted can be signaled by network. This can be signaled insystem information or in dedicated signaling. A list of mapping betweenc_id and carrier frequency can be signaled. The UE uses the c_idcorresponding to carrier frequency on which it has transmitted randomaccess preamble. In an embodiment value of c_id for PCell and PSCell iszero. The value of c_id for a SCell other than PSCell is signaled bynetwork in SI or dedicated signaling. Alternately, the value of c_id fora SCell other than PSCell is equal to serving cell index.

There can be several ways in which RA-RNTI can be computed using t_id,f_id and c_id. Various ways of computing RA-RNTI based on t_id, f_id andc_id is as follows:

RA-RNTI=1+Parameter 1+C1*Parameter 2+C1*C2*Parameter 3  (Eq. 4)

In equation 4, Parameter 1 is one of t_id or f_id or c_id, Parameter 2is one of [{t_id, f_id, c_id}−{Selected Parameter 1}], Parameter 3 isone of [{t_id, f_id, c_id}−{Selected Parameter 1}−{Selected Parameter2}], C1 is a number of distinct values of selected parameter 1, and C2is a number of distinct values of selected parameter 2.

One of the ways of computing RA-RNTI based on the above mechanism can bepre-defined in the system.

Method 2

In an embodiment of the proposed disclosure, RA-RNTI associated with thePRACH in which the Random Access Preamble is transmitted, is computedas:

RA-RNTI=1+t_id1+X1*t_id2+X1*X2*f_id  (Eq. 5)

In equation 5, t_id 1 is an index of the first slot of the PRACHtransmission occasion (0≤t_id<X1), and t_id 2 is an index of thesubframe in which PRACH transmission occasion starts or subframe inwhich first slot of PRACH transmission occasion is located (0≤t_id2<X2). The slots in a subframe are sequentially numbered starting fromzero. Depending on the SCS for Msg1 (or PRACH preamble) transmission,the number of slots in a subframe can vary from 1 to 8. The Maximumnumber of slots in a sub frame is 8, so X1 can be equal to 8. In anembodiment, the subframes in a radio frame are sequentially numberedstarting from zero. The Maximum number of subframe in a radio frame is10, so X2 can be equal to 10 if maximum RAR window size is one radioframe i.e. 10 ms.

FIG. 22 illustrates an embodiment of indexing slots for computingRA-RNTI based on Method 2 according to an embodiment of the disclosure.

Referring to FIG. 22 , if a maximum size of RAR window is greater thanone radio frame called N radio frames, then subframes in N consecutiveradio frames starting from radio frame with SFN 0 are indexedsequentially from zero. Subframes in SFN 0 to SFN N−1 are indexedsequentially start from zero. Subframes in SFN N to SFN 2N−1 are indexedsequentially start from zero and so on. In this case X2 can be equal to10*N. The subframes are indexed sequentially for N radio frames startingfrom first subframe of every radio frame with SFN which satisfiesequation SFN mod N=0.

FIG. 23 illustrates the other embodiment of indexing slots for computingRA-RNTI based on Method 2 according to an embodiment of the disclosure.

Referring to FIG. 23 , In an embodiment, if maximum size of RAR windowis greater than one radio frame called N sub frames, then every Nconsecutive subframes in SFN cycle, starting from the first subframe ofradio frame with SFN 0, are indexed sequentially starting from zero. Inthis case X2 can be equal to N.

In this example, f_id is an index of the PRACH transmission occasion, inascending order of frequency domain (0≤f_id<Y) and Y depends on numberof RACH transmission occasions supported in frequency domain in NR.

In an embodiment of the proposed disclosure, in which RAR window size isgreater than one radio frame, the RA-RNTI associated with the PRACH inwhich the Random Access Preamble is transmitted, can be computed as

RA-RNTI=1+t_id1+X1*t_id2+X1*X2*f_id+X1*X2*Y*(SFN_id mod (Wmax/Number ofslots in a radio frame))

In this example, SFN_id is the index of the first radio frame of thePRACH transmission occasion, and Wmax is maximum RAR window size inslots. The values of t_id1, t_id2 and f_id are as described above.

There are various ways in RA-RNTI can be computed based on t_id1, t_id2and f_id. These ways of computing RA-RNTI is based on t_id1, t_id2 andf_id is as follows:

RA-RNTI=1+Parameter 1+C1*Parameter 2+C1*C2*Parameter 3  (Eq. 6)

In equation 6, Parameter 1 is one of t_id1, t_id2, or f_id, Parameter 2is one of [{t_id1, t_id2, f_id}−{Selected Parameter 1}], Parameter 3 isone of [{t_id1, t_id2, f_id}−{Selected Parameter 1}−{Selected Parameter2}], C1 is a number of distinct values of selected parameter 1, and C2is a number of distinct values of selected parameter 2.

In another embodiment, random access preamble can be transmitted onfrequency F1 and RAR can be received on frequency F2. In this caseinformation about the carrier on which random access preamble istransmitted can also be included in RA-RNTI computation. For example,serving cell can configure a supplementary uplink (SUL) frequency calledFy. The uplink frequency of serving cell is called Fx. Serving cellconfigures PRACH resources on frequency Fy and Fx. Based on certaincriteria UE selects PRACH resource on either frequency Fy or frequencyFx for random access preamble transmission. If UE transmits randomaccess preamble on frequency Fy, it receives RAR in DL of serving cell.If the UE transmits random access preamble on frequency Fx, it receivesRAR in DL of serving cell. The RA-RNTI can be computed as follows:

RA-RNTI=1+t_id1+X1*t_id2+X1*X2*f_id+X1*X2*Y*c_id  (Eq. 7)

In equation 7, t_id1, t_id2, f_id, X1, X2 and Y are same as explainedearlier, and c_id is set to ‘1’ if UE transmits random access preambleon SUL or else c_id is set to ‘0.’

In an embodiment, the value of c_id to be used specific to a carrierfrequency (or specific to serving cell) on which random access preambleis transmitted can be signaled by network. This can be signaled insystem information or in dedicated signaling. A list of mapping betweenc_id and carrier frequency can be signaled. The UE uses the c_idcorresponding to carrier frequency on which it has transmitted randomaccess preamble. In an embodiment, value of c_id for PCell and PSCell iszero. The value of c_id for a SCell other than PSCell is signaled bynetwork in SI or dedicated signaling. Alternatively, the value of c_idfor a SCell other than PSCell is equal to serving cell index.

In an embodiment of the proposed disclosure, RA-RNTI associated with thePRACH in which the Random Access Preamble is transmitted, is computedas:

RA-RNTI=1+t_id1+X1*t_id2+X1*X2*f_id+X1*X2*Y*c_id+X1*X2*Y*Z*(SFN_idmod(Wmax/Number of slots in a radio frame))

In this example, SFN_id is the index of the first radio frame of thePRACH transmission occasion, and Wmax is maximum RAR window size inslots. The values of t_id1, t_id2, f_id, c_id are as defined earlier and0<=c_id<Z.

Note that other combinations, with respect to position of t_id1, t_id2,f_id and c_id in RA-RNTI equation are also possible. There are variousways in RA-RNTI can be computed based on t_id1, t_id2, f_id and c_id.Various ways of computing RA-RNTI based on t_id1, t_id2, f_id and c_idis as follows:

RA-RNTI=1+Parameter 1+C1*Parameter 2+C1*C2*Parameter3+C1*C2*C3*Parameter 4  (Eq. 8)

In equation 8, Parameter 1 is one of t_id1, t_id2, f_id, or c_id,Parameter 2 is one of [{t_id1, t_id2, f_id, c_id}−{Selected Parameter1}], Parameter 3 is one of [{t_id1, t_id2, f_id, c_id}−{SelectedParameter 1}−{Selected Parameter 2}], Parameter 3 is one of [{t_id1,t_id2, f_id, c_id}−{Selected Parameter 1}−{Selected Parameter2}−{Selected Parameter 3}], C1 is a number of distinct values ofselected parameter 1, C2 is a number of distinct values of selectedparameter 2, and C3 is a number of distinct values of selected parameter3.

Scenario 2: In time domain, multiple PRACH transmission occasions aresupported in one slot

Method 1

In this scenario, each orthogonal frequency division multiplexing (OFDM)symbol can be a PRACH transmission occasion in a slot. The RA-RNTIassociated with the PRACH in which the Random Access Preamble istransmitted, is computed as:

RA-RNTI=1+t_id1+X1*t_id2+X1*X2*f_id  (Eq. 9)

In equation 9, t_id1 is an index of the first OFDM symbol of the PRACHtransmission occasion (0≤t_id1<X1) and X1 can be 14, since each slot has14 OFDM symbols and PRACH transmission occasion can start in any symbol,and t_id2 is an index of the first slot of the PRACH transmissionoccasion (0≤t_id2<X2). The OFDM symbols in a slot are indexedsequentially starting from zero. If PRACH transmission occasion canstart only in some symbols in a slot, X1 can be smaller than 14. Forexample, if PRACH transmission occasion can only start in symbols 0, 4,8 and 12, X1 can be 4. Each of these symbols (e.g. 0, 4, 8, 12) wherePRACH transmission occasion can start can be logically indexedsequentially i.e., t_id1 for RACH transmission occasion starting insymbol 0 is 0, t_id1 for RACH transmission occasion starting in symbol 4is 1, t_id1 for RACH transmission occasion starting in symbol 8 is 2 andt_id1 for RACH transmission occasion starting in symbol 12 is 3.

In an embodiment, slots in radio frame are indexed sequentially startingfrom zero. The maximum number of slots in a radio frame is 80, so X2 canbe equal to 80 if maximum size of RAR window is one radio frame.

Alternatively, if PRACH transmission occasion can start only in someslots in a radio frame, X2 can be smaller than 80. For example, if PRACHtransmission occasion can only start in slot 0, 4, 8, and 12, X2 can be4. Each of these slots (e.g. 0, 4, 8, 12) where PRACH transmissionoccasion can start can be logically indexed sequentially (i.e. T_id2 forRACH transmission occasion starting in slot 0 is 0, T_id2 for RACHtransmission occasion starting in slot 4 is 1, T_id2 for RACHtransmission occasion starting in slot 8 is 2 and T_id2 for RACHtransmission occasion starting in slot 12 is 3).

In an embodiment, X2 can be set to a value depending on numerology orSCS. For example for SCS of 15 KHz it can be set to 10 as there are 10slots in a radio frame in this case. For SCS of 30 KHz it can be set to20 as there 20 slots in a radio frame in this case. For SCS of 60 KHz itcan be set to 40 as there are 40 slots in a radio frame in this case.For SCS of 120 KHz it can be set to 80 as there are 80 slots in a radioframe in this case.

In an embodiment, if maximum size of RAR window is greater than oneradio frame called N radio frames, then slots in every N consecutiveradio frames starting from radio frame with SFN 0, are indexedsequentially from zero. Slots in SFN 0 to SFN N−1 are indexedsequentially start from zero. Slots in SFN N to SFN 2N−1 are indexedsequentially start from zero and so on as shown in FIG. 19 below. Inthis case X2 can be equal to 80*N, as maximum number of slots in radioframe is 80 and maximum number of slots in N radio frames is N*80. Theslots are indexed sequentially for N consecutive radio frames startingfrom first slot of every radio frame with SFN which satisfies equationSFN mod N=0.

In another embodiment, if maximum size of RAR window is greater than oneradio frame called N sub frames, then slots in N consecutive sub framesstarting from 1st subframe in radio frame with SFN 0, are indexedsequentially from zero. Slots in subframe 0 to subframe N−1 are indexedsequentially start from zero. Slots in subframe N to subframe 2N−1 areindexed sequentially starting from zero and so on as shown in FIG. 20below. In this case X2 can be equal to 8*N as maximum number of slots ina subframe is 8. The slots are indexed sequentially for N subframesframes starting from first slot of every subframe ‘i’ in radio frame ‘j’which satisfies equation (j*10+i) mod N=0, where ‘j’ is the SFN of radioframe and ‘i’ is the subframe index (with radio frame subframes areindexed from 0 to 9 sequentially) of subframe within a radio frame.

In another embodiment, if maximum size of RAR window is called N slots,then starting from 1st slot of SFN 0, every N consecutive slots areindexed sequentially from zero to N−1 as shown in FIG. 21 . In this caseX2 can be equal to N.

The value of f_id is an index of the PRACH transmission occasion, inascending order of frequency domain; 0≤f_id<Y; Y depends on number ofRACH transmission occasions supported in frequency domain in NR.

In an embodiment of the proposed disclosure, in which RAR window size isgreater than one radio frame, RA-RNTI associated with the PRACH in whichthe Random Access Preamble is transmitted, can be computed as:

RA-RNTI=1+t_id1+X1*t_id2+X1*X2*f_id+X1*X2*Y*(SFN_id mod (Wmax/Number ofslots in a radio frame))

In this example, SFN_id is the index of the first radio frame of thePRACH transmission occasion, and Wmax is maximum RAR window size inslots. t_id1, t_id2 and f_id are as defined earlier.

Note that other combinations, with respect to position of t_id1, t_id2and f_id in RA-RNTI equation are also possible. There are various waysin RA-RNTI can be computed based on t_id1, t_id2 and f_id. Various waysof computing RA-RNTI based on t_id1, t_id2, f_id is as follows:

RA-RNTI=1+Parameter 1+C1*Parameter 2+C1*C2*Parameter 3  (Eq. 10)

In equation 10, Parameter 1 is one of t_id1, t_id2, or f_id, Parameter 2is one of [{t_id1, t_id2, f_id}−{Selected Parameter 1}], Parameter 3 isone of [{t_id1, t_id2, f_id}−{Selected Parameter 1}−{Selected Parameter2}], C1 is a number of distinct values of selected parameter 1, and C2is a number of distinct values of selected parameter 2.

In another embodiment, random access preamble can be transmitted onfrequency F1 and RAR can be received on frequency F2. In this caseinformation about the carrier on which random access preamble istransmitted can also be included in RA-RNTI computation. For example,serving cell can configure a supplementary uplink (SUL) frequency calledFy. The uplink frequency of serving cell is called Fx. Serving cellconfigures PRACH resources on frequency Fy and Fx. Based on certaincriteria UE selects PRACH resource on either frequency Fy or frequencyFx for random access preamble transmission. If UE transmits randomaccess preamble on frequency Fy, it receives RAR in DL of serving cell.If the UE transmits random access preamble on frequency Fx, it receivesRAR in DL of serving cell. The RA-RNTI can be computed as follows:

RA-RNTI=1+t_id1+X1*t_id2+X1*X2*f_id+X1*X2*Y*c_id  (Eq. 11)

In equation 11, t_id1, t_id2, f_id, X1, X2 and Y are same as explainedearlier. The value of c_id is set to ‘1’ if UE transmits random accesspreamble on SUL or else c_id is set to ‘0.’ In an embodiment, the valueof c_id to be used specific to a carrier frequency (or specific toserving cell) on which random access preamble is transmitted can besignaled by network. This can be signaled in system information or indedicated signaling. A list of mapping between c_id and carrierfrequency can be signaled. The UE uses the c_id corresponding to carrierfrequency on which it has transmitted random access preamble. In anembodiment value of c_id for PCell and PSCell is zero. The value of c_idfor a SCell other than PSCell is signaled by network in SI or dedicatedsignaling. Alternatively, the value of c_id for a SCell other thanPSCell is equal to serving cell index.

In an embodiment of the proposed disclosure, in which RAR window size isgreater than one radio frame, RA-RNTI associated with the PRACH in whichthe Random Access Preamble is transmitted, can be computed as:

RA-RNTI=RA-RNTI=1+t_id1+X1*t_id2+X1*X2*f_id+X1*X2*Y*c_id+X1*X2*Y*Z*(SFN_idmod(Wmax/Number of slots in a radio frame))

In this example, SFN_id is the index of the first radio frame of thePRACH transmission occasion, and Wmax is maximum RAR window size inslots. t_id1, t_id2 c_id and f_id are as defined earlier and 0<=c_id<Z.

Note that other combinations, with respect to position of t_id1, t_id2,f_id, c_id in RA-RNTI equation are also possible. There are various waysin RA-RNTI can be computed based on t_id1, t_id2, f_id and c_id. Variousways of computing RA-RNTI based on t_id1, t_id2, f_id and c_id is asfollows:

RA-RNTI=1+Parameter 1+C1*Parameter 2+C1*C2*Parameter3+C1*C2*C3*Parameter 4  (Eq. 12)

In equation 12, Parameter 1 is one of t_id1, t_id2, f_id, or c_id,Parameter 2 is one of [{t_id1, t_id2, f_id, c_id}−{Selected Parameter1}], Parameter 3 is one of [{t_id1, t_id2, f_id, c_id}−{SelectedParameter 1}−{Selected Parameter 2}], Parameter 4 is one of [{t_id1,t_id2, f_id, c_id}−{Selected Parameter 1}−{Selected Parameter2}−{Selected Parameter 3}], C1 is a number of distinct values ofselected parameter 1, C2 is a number of distinct values of selectedparameter 2, and C3 is a number of distinct values of selected parameter3.

Method 2

In this scenario, each OFDM symbol can be a PRACH transmission occasionin a slot. The RA-RNTI associated with the PRACH in which the RandomAccess Preamble is transmitted, is computed as:

RA-RNTI=1+t_id1+X1*t_id2+X1*X2*t_id3+X1*X2*X3*f_id  (Eq. 13)

In equation 13, t_id1 is an index of the first OFDM symbol of the PRACHtransmission occasion (0≤t_id1<X1) and t_id2 is an index of the firstslot of the PRACH transmission occasion, i.e., a slot in which RACHtransmission occasion starts (0≤t_id2<X2) The value of X1 can be 14,since each slot has 14 OFDM symbols and PRACH transmission occasion canstart in any symbol. OFDM symbols in a slot are indexed sequentiallystarting from zero. If PRACH transmission occasion can start only insome symbols in a slot, X1 can be smaller than 14. For example, if PRACHtransmission occasion can only start in symbols 0, 4, 8 and 12, X1 canbe 4. Each of these symbols (e.g. 0, 4, 8, 12) where PRACH transmissionoccasion can start can be logically indexed sequentially i.e. T_id1 forRACH transmission occasion starting in symbol 0 is 0, T_id1 for RACHtransmission occasion starting in symbol 4 is 1, T_id1 for RACHtransmission occasion starting in symbol 8 is 2 and T_id1 for RACHtransmission occasion starting in symbol 12 is 3.

The maximum number of slots in a subframe is 8, so X2 can be equal to 8;slots in subframe are indexed sequentially starting from zero.

Alternately, if PRACH transmission occasion can start only in some slotsin a sub frame, X2 can be smaller than 8. For example, if PRACHtransmission occasion can only start in slot 0 and 4, X2 can be 4. Eachof these slots (e.g. 0, 4) where PRACH transmission occasion can startcan be logically indexed sequentially (i.e. T_id2 for RACH transmissionoccasion starting in slot 0 is 0, T_id2 for RACH transmission occasionstarting in slot 4 is 1).

In an embodiment, X2 can be set to a value depending on numerology orSCS. For example for SCS of 15 KHz it can be set to 1 as there is 1slots in a sub frame in this case. For SCS of 30 KHz it can be set to 2as there 2 slots in a sub frame in this case. For SCS of 60 KHz it canbe set to 4 as there are 4 slots in a sub frame in this case. For SCS of120 KHz it can be set to 8 as there are 8 slots in a sub frame in thiscase.

t_id 3 is an index of the subframe in which PRACH transmission occasionstarts or subframe in which first slot of PRACH transmission occasion islocated; 0≤t_id 3<X3; In an embodiment, the subframes in a radio frameare sequentially numbered starting from zero. Maximum number of subframein a radio frame is 10, so X3 can be equal to 10 if the maximum RARwindow size is one radio frame;

In another embodiment, if maximum size of RAR window is greater than oneradio frame called N radio frames, then subframes in N consecutive radioframes starting from radio frame with SFN 0 are indexed sequentiallyfrom zero. Subframes in SFN 0 to SFN N−1 are indexed sequentially startfrom zero. Subframes in SFN N to SFN 2N−1 are indexed sequentially startfrom zero and so on as shown in FIG. 21 below. In this case X3 can beequal to 10*N. The subframes are indexed sequentially for N radio framesstarting from first subframe of every radio frame with SFN whichsatisfies equation SFN mod N=0.

In an embodiment, if maximum size of RAR window is greater than oneradio frame called N sub frames, then every N consecutive subframes inSFN cycle, starting from the first subframe of radio frame with SFN 0,are indexed sequentially starting from zero as shown in FIG. 23 . Inthis case X3 can be equal to N.

The value of f_id is an index of the PRACH transmission occasion, inascending order of frequency domain; 0≤f_id<Y; Y depends on number ofRACH transmission occasions supported in frequency domain. In anembodiment, if multiple resource pools (e.g. separate resource pool forbeam failure recovery, handover, etc.) for RACH are configured,frequency division multiplexed PRACH transmission occasions in eachresource pool can be independently numbered starting from zero. Forexample, if there are two resource pools, resource pool 1 having twofrequency division multiplexed PRACH transmission occasions and resourcepool 2 having four frequency division multiplexed PRACH transmissionoccasions, the frequency division multiplexed PRACH transmissionoccasions are numbered 0 and 1 in resource pool 1 and the frequencydivision multiplexed PRACH transmission occasions are numbered 0, 1, 2,and 3 in resource pool 2.

In another embodiment, if multiple resource pools for RACH areconfigured, frequency division multiplexed PRACH transmission occasionsare numbered starting from zero across resource pools. For example, letus say there are two resource pools. In resource pool 1 there are twofrequency division multiplexed PRACH transmission occasions. In resourcepool 2 there are four frequency division multiplexed PRACH transmissionoccasions. The frequency division multiplexed PRACH transmissionoccasions are numbered 0 and 1 in resource pool 1. The frequencydivision multiplexed PRACH transmission occasions are numbered 2, 3, 4,and 5. In another embodiment, if multiple resource pools for RACH areconfigured, network may configure the starting f_id to be used for eachresource pool. The FDM PRACH transmission occasions in a resource poolare sequentially numbered starting from f_id indicated by network forthat resource pool.

In an embodiment of the proposed disclosure, in which RAR window size isgreater than one radio frame, RA-RNTI associated with the PRACH in whichthe Random Access Preamble is transmitted, can be computed as:

RA-RNTI=1+t_id1+X1*t_id2+X1*X2*t_id3+X1*X2*X3*f_id+X1*X2*X3*Y*(SFN_idmod(Wmax/Number of slots in a radio frame))

In this example, SFN_id is the index of the first radio frame of thePRACH transmission occasion, and Wmax is maximum RAR window size inslots. t_id1, t_id2, t_id3 and f_id are as defined earlier.

Note that other combinations, with respect to position of t_id1, t_id2,t_id3 and f_id in RA-RNTI equation are also possible. There are variousways in RA-RNTI can be computed based on t_id1, t_id2, t_id3 and f_id.Various ways of computing RA-RNTI based on t_id1, t_id2, t_id3 and f_idis as follows:

RA-RNTI=1+Parameter 1+C1*Parameter 2+C1*C2*Parameter3+C1*C2*C3*Parameter 4  (Eq. 14)

In equation 14, Parameter 1 is one of id1, t_id2, t_id3, or f_id,Parameter 2 is one of [{t_id1, t_id2, t_id3, f_id}−{Selected Parameter1}], Parameter 3 is one of [{t_id1, t_id2, t_id3, f_id}−{SelectedParameter 1}−{Selected Parameter 2}], Parameter 4 is one of [{t_id1,t_id2, t_id3, f_id}−{Selected Parameter 1}−{Selected Parameter2}−{Selected Parameter 3}], C1: is a number of distinct values ofselected parameter 1, C2 is a number of distinct values of selectedparameter 2, and C3 is a number of distinct values of selected parameter3.

In another embodiment, random access preamble can be transmitted onfrequency F1 and RAR can be received on frequency F2. In this caseinformation about the carrier on which random access preamble istransmitted can also be included in RA-RNTI computation. For example,serving cell can configure a supplementary uplink (SUL) frequency calledFy. The uplink frequency of serving cell is called Fx. Serving cellconfigures PRACH resources on frequency Fy and Fx. Based on certaincriteria UE selects PRACH resource on either frequency Fy or frequencyFx for random access preamble transmission. If UE transmits randomaccess preamble on frequency Fy, it receives RAR in DL of serving cell.If the UE transmits random access preamble on frequency Fx, it receivesRAR in DL of serving cell. The RA-RNTI can be computed as follows:

RA-RNTI=1+t_id1+X1*t_id2+X1*X2*t_id3+X1*X2*X3*f_id+X1*X2*X3*Y*c_id  (Eq.15)

In equation 15, t_id1, t_id2, f_id, X1, X2, X3 and Y are same asexplained earlier, and c_id is set to ‘1’ if UE transmits random accesspreamble on SUL or else c_id is set to ‘0.’

In an embodiment, the value of c_id to be used specific to a carrierfrequency (or specific to serving cell) on which random access preambleis transmitted can be signaled by network. This can be signaled insystem information or in dedicated signaling. A list of mapping betweenc_id and carrier frequency can be signaled. The UE uses the c_idcorresponding to carrier frequency on which it has transmitted randomaccess preamble. In an embodiment, value of c_id for PCell and PSCell iszero. The value of c_id for a SCell other than PSCell is signaled bynetwork in SI or dedicated signaling. Alternatively, the value of c_idfor a SCell other than PSCell is equal to serving cell index.

Note that other combinations, with respect to position of t_id1, t_id2,t_id3, f_id, c_id in RA-RNTI equation are also possible. There arevarious ways in RA-RNTI can be computed based on t_id1, t_id2, t_id3,f_id and c_id. Various ways of computing RA-RNTI based on t_id1, t_id2,t_id3, f_id and c_id is as follows:

RA-RNTI=1+Parameter 1+C1*Parameter 2+C1*C2*Parameter3+C1*C2*C3*Parameter 4+C1*C2*C3*C4*Parameter 5  (Eq. 16)

In equation 16, Parameter 1 is one of t_id1, t_id2, t_id3, f_id, orc_id, Parameter 2 is one of [{t_id1, t_id2, t_id3, f_id, c_id}−{SelectedParameter 1}], Parameter 3 is one of [{t_id1, t_id2, t_id3, f_id,c_id}−{Selected Parameter 1}−{Selected Parameter 2}], Parameter 4 is oneof [{t_id1, t_id2, t_id3, f_id, c_id}−{Selected Parameter 1}−{SelectedParameter 2}−{Selected Parameter 3}], Parameter 5 is one of [{t_id1,t_id2, t_id3, f_id, c_id}−{Selected Parameter 1}−{Selected Parameter2}−{Selected Parameter 3}−{Selected Parameter 4}], C1 is a number ofdistinct values of selected parameter 1, C2 is a n umber of distinctvalues of selected parameter 2, C3 is a n umber of distinct values ofselected parameter 3, and C4 is a number of distinct values of selectedparameter 4.

SUL Indication Method

In an embodiment, instead of updating the RA-RNTI calculation to includethe SUL indication, SUL indication can be indicated in RAR. Theindication can be in MAC subheader with RAPID or can be included in MACRAR. SUL indication is set to one by gNB for PRACH preamble received onSUL frequency or carrier. Otherwise, it is set to zero. RAR isconsidered as successful in following manner

If a downlink assignment has been received on the NR-PDCCH for theRA-RNTI and the received TB is successfully decoded:

-   -   If the UE has transmitted RACH on SUL:    -   if the Random Access Response contains a Random Access Preamble        identifier corresponding to the transmitted Random Access        Preamble and SUL indication in Random Access Response is set to        ‘ 1,’ RAR is considered as successfully received.    -   else (If the UE has not transmitted RACH on SUL):    -   if the Random Access Response contains a Random Access Preamble        identifier corresponding to the transmitted Random Access        Preamble and SUL indication in Random Access Response is set to        ‘0,’ RAR is considered as successfully received.

In an embodiment, instead of updating the RA-RNTI calculation to includethe SUL indication, SUL indication can be indicated in DCI transmittedon NR-PDCCH for RAR. SUL indication is set to one in DCI transmitted onNR-PDCCH gNB if RAR is corresponding to PRACH preamble transmitted onSUL. Otherwise it is set to zero. RAR is considered as successful infollowing manner

-   -   If the UE has transmitted RACH on SUL:    -   If a downlink assignment including SUL indication set to one has        been received on the NR-PDCCH for the RA-RNTI and the received        TB is successfully decoded:    -   And if the Random Access Response contains a Random Access        Preamble identifier corresponding to the transmitted Random        Access Preamble, RAR is considered as successfully received    -   else if the UE has not transmitted RACH on SUL:    -   If a downlink assignment including SUL indication set to zero        has been received on the NR-PDCCH for the RA-RNTI and the        received TB is successfully decoded:    -   And if the Random Access Response contains a Random Access        Preamble identifier corresponding to the transmitted Random        Access Preamble, RAR is considered as successfully received

Preamble ID Extension Mechanism

There are 64 unique random access preamble sequences wherein each randomaccess preamble sequence is uniquely identified by 6 bit random accesspreamble index or random access preamble identifier. In next generationwireless communication system, random access preambles are used forvarious purposes such as, to identify the Msg3 sizes, to identify the ondemand SI requests, to identify the DL TX beams and so on. So 64 randomaccess preamble sequences are not enough. In case the number of randomaccess preamble sequences is increased, more bits are needed to uniquelyidentify each random access preamble sequence. For example, if randomaccess preamble sequences are increased to 256 then 8 bits are needed touniquely identify each random access preamble sequence. If random accesspreamble sequences are increased to 1024 then 10 bits are needed touniquely identify each random access preamble sequence.

The RAPID field in a RAR identifies the transmitted random accesspreamble. The RAPID field is 6 bits and is included in MAC subheader. Incase the number of random access preambles is increased, 6 bits cannotuniquely identify the transmitted random access preamble. Onestraightforward method to overcome this problem is to increase the RAPIDfield size. However this would lead to increase in the header overheadas MAC subheader size will be doubled from 1 byte to 2 bytes.

For RAR, gNB first transmits scheduling assignment (DCI) on NR-PDCCH.NR-PDCCH is addressed to RA-RNTI. The Transport block including the RARis then transmitted over NR-PDSCH. The scheduling assignment on NR-PDCCHindicates scheduling information about the TB transmitted over NR-PDSCH.

FIG. 24 illustrates transmitting a random access preamble identifier toa UE according to an embodiment of the disclosure.

Referring to FIG. 24 , it is proposed that ‘X’ Least significant bits(Lsbs) of random access preamble identifier or index is included in MACsubheader. For example, X equals 6 bits, if the length of RAPID field inMAC subheader is 6 bits. The remaining or Y Most significant bits (Msbs)of random access preamble identifier or index is included in schedulingassignment (DCI) which is transmitted on NR-PDCCH for RAR. As shown inFIG. 24 , a UE 2400 receives NR-PDCCH addressed to RA-RNTI from gNB 2410in operation 2420. After operation 2420, the UE 2400 receives NR-PDSCHincluding RAR from the gNB 2410 in operation 2430. On receiving the RAR,UE will obtain the ‘X’ Lsbs of random access preamble identifier orindex from MAC subheader. The remaining or Y Msbs of random accesspreamble identifier or index are obtained from the scheduling assignment(DCI) which is received on NR-PDCCH for RA-RNTI. If the ‘X’ Lsbs ofrandom access preamble identifier or index from MAC subheader is equalto ‘X’ Lsbs of random access preamble identifier or index correspondingto the transmitted random access preamble and remaining or Y Msbs ofrandom access preamble identifier or index obtained from the schedulingassignment is equal to remaining ‘Y’ Lsbs of random access preambleidentifier or index corresponding to the transmitted random accesspreamble then UE considers that random access preamble corresponding toreceived RAR and random access preamble transmitted by it is same.

FIGS. 25 and 26 illustrate transmitting a random access preambleidentifier to UE according to an embodiment of the disclosure.

Referring to FIGS. 25 and 26 , it is proposed that ‘X’ Lsbs of randomaccess preamble identifier or index is included in MAC subheader. Theremaining or Y Msbs of random access preamble identifier or index isincluded in MAC RAR. Referring to FIG. 25 , a UE 2500 receives NR-PDCCHaddressed to RA-RNTI from gNB 2510 in operation 2520. After operation2520, the UE 2500 receives NR-PDSCH including RAR from the gNB 2510 inoperation 2530. On receiving the RAR, UE will obtain the ‘X’ Lsbs ofrandom access preamble identifier or index from MAC subheader 2600 andremaining or Y Msbs of random access preamble identifier or index fromthe MAC RAR 2610. If the ‘X’ Lsbs of random access preamble identifieror index from MAC subheader is equal to ‘X’ Lsbs of random accesspreamble identifier or index corresponding to the transmitted randomaccess preamble and remaining or Y Msbs of random access preambleidentifier or index obtained from the MAC RAR is equal to remaining ‘Y’Lsbs of random access preamble identifier or index corresponding to thetransmitted random access preamble then UE considers that random accesspreamble corresponding to received RAR and random access preambletransmitted by it is same.

In an alternate embodiment, it is proposed that ‘X’ Lsbs (Leastsignificant bits) of random access preamble identifier or index isincluded in MAC subheader. The remaining or Z Msbs (Most significantbits) of random access preamble identifier or index is included inRA-RNTI calculation. On receiving the RAR, UE will obtain the ‘X’ Lsbsof random access preamble identifier or index from MAC subheader. If the‘X’ Lsbs of random access preamble identifier or index from MACsubheader is equal to ‘X’ Lsbs of random access preamble identifier orindex corresponding to the transmitted random access preamble then UEconsiders that random access preamble corresponding to receive RAR andrandom access preamble transmitted by it is same.

RA-RNTI Calculation with Preamble Info

After transmitting the PRACH preamble, UE monitors the PDCCH of theSPCell for Random Access Response(s) identified by the RA-RNTI(s) duringthe RAR window. The RA-RNTI is computed as described in further detailbelow.

Scenario 1: In time domain, only one PRACH transmission occasion issupported in one slot

Method 1

In this scenario, the RA-RNTI associated with the PRACH in which theRandom Access Preamble is transmitted, is computed as:

RA-RNTI=1+t_id+X*f_id+X*Y*P_id

OR

RA-RNTI=1+t_id+X*P_id+X*2Z*f_id

OR

RA-RNTI=1+P_id+2Z*t_id++X*2Z*f_id

In this example, t_id is an index of the first slot of the PRACHtransmission occasion; 0≤t_id<X; the slots in a radio frame aresequentially numbered starting from zero. Depending on the SCS for Msg1(or PRACH preamble) transmission, number of slots in a radio frame canvary from 10 to 80 as shown in Table 2 below. The maximum number ofslots in a radio frame is 80, so X can be equal to 80 if maximum RARwindow size is one radio frame i.e. 10 ms.

TABLE 2 SCS for determining # of slots in # of slots in RACH slot asubframe a radio frame 15 KHz 1 10 30 KHz 2 20 60 KHz 4 40 120 KHz  8 80

Alternately, if PRACH transmission occasion can start only in some slotsin a radio frame, X can be smaller than 80. For example, if PRACHtransmission occasion can only start in slots 0, 4, 8 and 12, X can be 4as there are four possible slots where PRACH transmission occasion canstart. Each of these slots (0, 4, 8, 12 in the example) where PRACHtransmission can start are logically numbered sequentially (i.e. T_idfor RACH transmission occasion starting in slot 0 is 0, T_id for RACHtransmission occasion starting in slot 4 is 1, T_id for RACHtransmission occasion starting in slot 8 is 2 and T_id for RACHtransmission occasion starting in slot 12 is 3.

In an embodiment, X can be set to a value depending on numerology orSCS. For example for SCS of 15 KHz it can be set to 10 as there are 10slots in a radio frame in this case. For SCS of 30 KHz it can be set to20 as there 20 slots in a radio frame in this case. For SCS of 60 KHz itcan be set to 40 as there are 40 slots in a radio frame in this case.For SCS of 120 KHz it can be set to 80 as there are 80 slots in a radioframe in this case. The slots in a radio frame are sequentially numberedstarting from zero.

In an embodiment, if maximum size of RAR window is greater than oneradio frame called N radio frames, then slots in every N consecutiveradio frames starting from radio frame with SFN 0, are indexedsequentially from zero. Slots in SFN 0 to SFN N−1 are indexedsequentially start from zero. Slots in SFN N to SFN 2N−1 are indexedsequentially start from zero and so on as shown in FIG. 19 below. Inthis case X can be equal to 80*N, as maximum number of slots in radioframe is 80 and maximum number of slots in N radio frames is N*80. Theslots are indexed sequentially for N consecutive radio frames startingfrom first slot of every radio frame with SFN which satisfies equationSFN mod N=0.

In another embodiment, if the maximum size of a RAR window is greaterthan one radio frame called N sub frames, then slots in N consecutivesub frames starting from 1st subframe in radio frame with SFN 0, areindexed sequentially from zero. Slots in subframe 0 to subframe N−1 areindexed sequentially start from zero. Slots in subframe N to subframe2N−1 are indexed sequentially starting from zero and so on as shown inFIG. 20 below. In this case X can be equal to 8*N as maximum number ofslots in a subframe is 8. The slots are indexed sequentially for Nsubframes frames starting from first slot of every subframe ‘i’ in radioframe ‘j’ which satisfies equation (j*10+i) mod N=0, where ‘j’ is theSFN of radio frame and ‘i’ is the subframe index (with radio framesubframes are indexed from 0 to 9 sequentially) of subframe within aradio frame.

In another embodiment, if the maximum size of a RAR window is called Nslots, then starting from 1st slot of SFN 0, every N consecutive slotsare indexed sequentially from zero to N−1 as shown in FIG. 21 . In thiscase X can be equal to N.

In this example, f_id is an index of the PRACH transmission occasion, inascending order of frequency domain; 0≤f_id<Y; and Y depends on numberof RACH transmission occasions supported in frequency domain in NR. Inan embodiment, if multiple resource pools (e.g. separate resource poolfor beam failure recovery, handover, etc.) for RACH are configured,frequency division multiplexed PRACH transmission occasions in eachresource pool can be independently numbered starting from zero. Forexample, if there are two resource pools, resource pool 1 having twofrequency division multiplexed PRACH transmission occasions and resourcepool 2 having four frequency division multiplexed PRACH transmissionoccasions, the frequency division multiplexed PRACH transmissionoccasions are numbered 0 and 1 in resource pool 1 and the frequencydivision multiplexed PRACH transmission occasions are numbered 0, 1, 2,and 3 in resource pool 2.

In another embodiment, if multiple resource pools for RACH areconfigured, frequency division multiplexed PRACH transmission occasionsare numbered starting from zero across resource pools. For example, letus say there are two resource pools. In resource pool 1 there are twofrequency division multiplexed PRACH transmission occasions. In resourcepool 2 there are four frequency division multiplexed PRACH transmissionoccasions. The frequency division multiplexed PRACH transmissionoccasions are numbered 0 and 1 in resource pool 1. The frequencydivision multiplexed PRACH transmission occasions are numbered 2, 3, 4,and 5. In another embodiment, if multiple resource pools for RACH areconfigured, network may configure the starting f_id to be used for eachresource pool. The FDM PRACH transmission occasions in a resource poolare sequentially numbered starting from f_id indicated by network forthat resource pool.

In this example, P_id is a value of Z Msbs of Random Access PreambleIdentifier of Random access preamble transmitted by UE. Z ispre-defined. For example if Z is 2 bits, then P_id is 0 (if 2 Msbs ofRandom Access Preamble Identifier are ‘00’) or 1 (if 2 Msbs of RandomAccess Preamble Identifier are ‘01’) or 2 (if 2 Msbs of Random AccessPreamble Identifier are ‘10’) or 3 (if 2 Msbs of Random Access PreambleIdentifier are ‘11’).

Note that other combinations, with respect to position of t_id, f_id andP_id in RA-RNTI equation are also possible. Various ways of computingRA-RNTI based on t_id, f_id and P_id is as follows:

RA-RNTI=1+Parameter 1+C1*Parameter 2+C1*C2*Parameter 3.

In this example, Parameter 1 is one of t_id, f_id, or P_id, Parameter 2is one of [{t_id, f_id, P_id}−{Selected Parameter 1}], Parameter 3 isone of [{t_id, f_id, P_id}−{Selected Parameter 1}−{Selected Parameter2}], C1 is a number of distinct values of selected parameter 1, C2 is anumber of distinct values of selected parameter 2.

In another embodiment, random access preamble can be transmitted onfrequency F1 and RAR can be received on frequency F2. In this caseinformation about the carrier on which random access preamble istransmitted can also be included in RA-RNTI computation. For example,serving cell can configure a supplementary uplink (SUL) frequency calledFy. The uplink frequency of serving cell is called Fx. Serving cellconfigures PRACH resources on frequency Fy and Fx. Based on certaincriteria UE selects PRACH resource on either frequency Fy or frequencyFx for random access preamble transmission. If UE transmits randomaccess preamble on frequency Fy, it receives RAR in DL of serving cell.If the UE transmits random access preamble on frequency Fx, it receivesRAR in DL of serving cell. The RA-RNTI can be computed as follows:

RA-RNTI=1+t_id+X*f_id+X*Y*P_id+X*Y*2Z*c_id

OR

RA-RNTI=1+t_id+X*f_id+X*Y*c_id+X*Y*2*P_id

OR

RA-RNTI=1+t_id+X*P_id+X*2Z*f_id+X*Y*2Z*c_id

OR

RA-RNTI=1+P_id+2Z*t_id++X*2Z*f_id+X*Y*2Z*c_id

The values of t_id, f_id, P_id, X, Z and Y are explained. The value c_idis set to ‘1’ if UE transmits random access preamble on SUL or else c_idis set to ‘0.’ In an embodiment, the value of c_id to be used specificto a carrier frequency (or specific to serving cell) on which randomaccess preamble is transmitted can be signaled by network. This can besignaled in system information or in dedicated signaling. A list ofmapping between c_id and carrier frequency can be signaled. The UE usesthe c_id corresponding to carrier frequency on which it has transmittedrandom access preamble. In an embodiment value of c_id for PCell andPSCell is zero. The value of c_id for a SCell other than PSCell issignaled by network in SI or dedicated signaling. Alternatively, thevalue of c_id for a SCell other than PSCell is equal to serving cellindex.

Note that other combinations, with respect to position of t_id, f_id,P_id and c_id in RA-RNTI equation are also possible. Various ways ofcomputing RA-RNTI based on t_id, f_id, P_id and c_id are as follows:

RA-RNTI=1+Parameter 1+C1*Parameter 2+C1*C2*Parameter3+C1*C2*C3*Parameter 4

In this example, Parameter 1 is one of t_id, f_id, P_id, or c_id,Parameter 2 is one of [{t_id, f_id, P_id, c_id}−{Selected Parameter 1}],Parameter 3 is one of [{t_id, f_id, P_id, c_id}−{Selected Parameter1}−{Selected Parameter 2}], Parameter 4 is one of [{t_id, f_id, P_id,c_id}−{Selected Parameter 1}−{Selected Parameter 2}−{Selected Parameter3}], C1 is a number of distinct values of Selected parameter 1, C2 is anumber of distinct values of Selected parameter 2, C3 is a number ofdistinct values of Selected parameter 3.

Method 2

In this scenario, the RA-RNTI associated with the PRACH in which theRandom Access Preamble is transmitted, is computed as:

RA-RNTI=1+t_id1+X1*t_id2+X1*X2*f_id+X1*X2*Y*P_id

OR

RA-RNTI=1+P_id+2Z*t_id1+X1*2Z*t_id2+X1*2Z*X2*f_id

OR

RA-RNTI=1+t_id1+X1*P_id+X1*2Z*t_id2+X1*2Z*X2*f_id

OR

RA-RNTI=1+t_id1+X1*t_id2+X1*X2*P_id+X1*X2*2Z*f_id

In this example, t_id 1 is an index of the first slot of the PRACHtransmission occasion (0≤t_id<X1) and t_id 2 is an index of the subframein which PRACH transmission occasion starts or subframe in which firstslot of PRACH transmission occasion is located (0≤t_id 2<X2. The slotsin a subframe frame are sequentially numbered starting from zero.Depending on the SCS for Msg1 (or PRACH preamble) transmission, numberof slots in a subframe frame can vary from 1 to 8. Maximum number ofslots in a sub frame is 8, so X1 can be equal to 8;

The subframes in a radio frame are sequentially numbered starting fromzero. Maximum number of subframe in a radio frame is 10, so X2 can beequal to 10 if maximum RAR window size is one radio frame i.e. 10 ms.

In another embodiment, if maximum size of RAR window is greater than oneradio frame called N radio frames, then subframes in N consecutive radioframes starting from radio frame with SFN 0 are indexed sequentiallyfrom zero. Subframes in SFN 0 to SFN N−1 are indexed sequentially startfrom zero. Subframes in SFN N to SFN 2N−1 are indexed sequentially startfrom zero and so on as shown in FIG. 21 below. In this case X2 can beequal to 10*N. The subframes are indexed sequentially for N radio framesstarting from first subframe of every radio frame with SFN whichsatisfies equation SFN mod N=0.

In an embodiment, if maximum size of RAR window is greater than oneradio frame called N sub frames, then every N consecutive subframes inSFN cycle, starting from the first subframe of radio frame with SFN 0,are indexed sequentially starting from zero as shown in FIG. 23 . Inthis case X2 can be equal to N.

The value of f_id is an index of the PRACH transmission occasion, inascending order of frequency domain; 0≤f_id<Y; Y depends on number ofRACH transmission occasions supported in frequency domain in NR.

In this example, P_id is a value of Z Msbs of Random Access PreambleIdentifier of Random access preamble transmitted by UE. Z ispre-defined. For example if Z is 2 bits, then P_id is 0 (if 2 Msbs ofRandom Access Preamble Identifier are ‘00’) or 1 (if 2 Msbs of RandomAccess Preamble Identifier are ‘01’) or 2 (if 2 Msbs of Random AccessPreamble Identifier are ‘10’) or 3 (if 2 Msbs of Random Access PreambleIdentifier are ‘11’).

Note that other combinations, with respect to position of t_id1, t_id2,f_id, P_id in RA-RNTI equation are also possible. Various ways ofcomputing RA-RNTI based on t_id1, t_id2, f_id and P_id are as follows:

RA-RNTI=1+Parameter 1+C1*Parameter 2+C1*C2*Parameter3+C1*C2*C3*Parameter 4

In this example, Parameter 1 is one of t_id1, t_id2, f_id, or P_id,Parameter 2 is one of [{t_id1, t_id2, f_id, P_id}−{Selected Parameter1}], Parameter 3 is one of [{t_id1, t_id2, f_id, P_id}−{SelectedParameter 1}−{Selected Parameter 2}], Parameter 4 is one of [{t_id1,t_id2, f_id, P_id}−{Selected Parameter 1}−{Selected Parameter2}−{Selected Parameter 3}], C1 is a number of distinct values ofselected parameter 1, C2 is a number of distinct values of selectedparameter 2, and C3 is a number of distinct values of selected parameter3.

In another embodiment, random access preamble can be transmitted onfrequency F1 and RAR can be received on frequency F2. In this caseinformation about the carrier on which random access preamble istransmitted can also be included in RA-RNTI computation. For example,serving cell can configure a supplementary uplink (SUL) frequency calledFy. The uplink frequency of serving cell is called Fx. Serving cellconfigures PRACH resources on frequency Fy and Fx. Based on certaincriteria UE selects PRACH resource on either frequency Fy or frequencyFx for random access preamble transmission. If UE transmits randomaccess preamble on frequency Fy, it receives RAR in DL of serving cell.If the UE transmits random access preamble on frequency Fx, it receivesRAR in DL of serving cell. The RA-RNTI can be computed as follows:

RA-RNTI=1+t_id1+X1*t_id2+X1*X2*f_id+X1*X2*Y*ID+X1*X2*Y*2*P_id

OR

RA-RNTI=1+t_id1+X1*t_id2+X1*X2*f_id+X1*X2*Y*P_id+X1*X2*Y*2Z*ID

OR

RA-RNTI=1+P_id+2Z*t_id1+X1*2Z*t_id2+X1*2Z*X2*f_id+X1*X2*Y*2Z*ID

OR

RA-RNTI=1+t_id1+X1*P_id+X1*2Z*t_id2+X1*2Z*X2*f_id+X1*X2*Y*2Z*ID

OR

RA-RNTI=1+t_id1+X1*t_id2+X1*X2*P_id+X1*X2*2Z*f_id+X1*X2*Y*2Z*ID

The values of t_id1, t_id2, f_id, P_id, X1, X2, Z and Y are explainedearlier. The value of c_id is set to ‘1’ if UE transmits random accesspreamble on SUL or else c_id is set to ‘0.’ In an embodiment, the valueof c_id to be used specific to a carrier frequency (or specific toserving cell) on which random access preamble is transmitted can besignaled by network. This can be signaled in system information or indedicated signaling. A list of mapping between c_id and carrierfrequency can be signaled. The UE uses the c_id corresponding to carrierfrequency on which it has transmitted random access preamble. In anembodiment value of c_id for PCell and PSCell is zero. The value of c_idfor a SCell other than PSCell is signaled by network in SI or dedicatedsignaling. Alternatively, the value of c_id for a SCell other thanPSCell is equal to serving cell index.

Note that other combinations, with respect to position of t_id1, t_id2,f_id, P_id and c_id in RA-RNTI equation are also possible. Various waysof computing RA-RNTI based on t_id1, t_id2, f_id, P_id and c_id are asfollows:

RA-RNTI=1+Parameter 1+C1*Parameter 2+C1*C2*Parameter3+C1*C2*C3*Parameter 4+C1*C2*C3*C4*Parameter 5

In this example, Parameter 1 is one of t_id1, t_id2, f_id, P_id, orc_id, Parameter 2 is one of [{t_id1, t_id2, f_id, P_id, c_id}−{SelectedParameter 1}], Parameter 3 is one of [{t_id1, t_id2, f_id, P_id,c_id}−{Selected Parameter 1}−{Selected Parameter 2}], Parameter 4 is oneof [{t_id1, t_id2, f_id, P_id, c_id}−{Selected Parameter 1}−{SelectedParameter 2}−{Selected Parameter 3}], Parameter 5 is one of [{t_id1,t_id2, f_id, P_id, c_id}−{Selected Parameter 1}−{Selected Parameter2}−{Selected Parameter 3}−{Selected Parameter 4}], C1 is a number ofdistinct values of Selected parameter 1, C2 is a number of distinctvalues of Selected parameter 2, C3 is a number of distinct values ofSelected parameter 3, and C4 is a number of distinct values of Selectedparameter 4.

Scenario 2: In time domain, multiple PRACH transmission occasions aresupported in one slot

Method 1

In this scenario, each OFDM symbol can be a transmission occasion in aslot. The RA-RNTI associated with the PRACH in which the Random AccessPreamble is transmitted, is computed as:

RA-RNTI=1+t_id1+X1*t_id2+X1*X2*f_id+X1*X2*Y*P_id

OR

RA-RNTI=1+P_id+2Z*t_id1+X1*2Z*t_id2+X1*2Z*X2*f_id

OR

RA-RNTI=1+t_id1+X1*P_id+X1*2Z*t_id2+X1*2Z*X2*f_id

OR

RA-RNTI=1+t_id1+X1*t_id2+X1*X2*P_id+X1*X2*2Z*f_id

In this example, t_id1 is an index of the first OFDM symbol of the PRACHtransmission occasion (0≤t_id1<X1), and t_id2 is an index of the firstslot of the PRACH transmission occasion (0≤t_id2<X2). In this example,X1 can be 14, since each slot has 14 OFDM symbols and PRACH transmissionoccasion can start in any symbol. OFDM symbols in a slot are indexedsequentially starting from zero. If PRACH transmission occasion canstart only in some symbols in a slot, X1 can be smaller than 14. Forexample, if PRACH transmission occasion can only start in symbols 0, 4,8, and 12, X1 can be 4. Each of these symbols (e.g. 0, 4, 8, 12) wherePRACH transmission occasion can start are logically indexed sequentiallyi.e. In this example, t_id1 for RACH transmission occasion starting insymbol 0 is 0, t_id1 for RACH transmission occasion starting in symbol 4is 1, t_id1 for RACH transmission occasion starting in symbol 8 is 2 andt_id1 for RACH transmission occasion starting in symbol 12 is 3.

In an embodiment, slots in radio frame are indexed sequentially startingfrom zero. The maximum number of slots in a radio frame is 80, so X2 canbe equal to 80 if maximum size of RAR window is one radio frame.

Alternately, if PRACH transmission occasion can start only in some slotsin a radio frame, X2 can be smaller than 80. For example, if PRACHtransmission occasion can only start in slot 0, 4, 8, and 12, X2 can be4. Each of these slots (e.g. 0, 4, 8, 12) where PRACH transmissionoccasion can start can be logically indexed sequentially (i.e. T_id2 forRACH transmission occasion starting in slot 0 is 0, t_id2 for RACHtransmission occasion starting in slot 4 is 1, t_id2 for RACHtransmission occasion starting in slot 8 is 2 and t_id2 for RACHtransmission occasion starting in slot 12 is 3).

In an embodiment, X2 can be set to a value depending on numerology orSCS. For example for SCS of 15 KHz it can be set to 10 as there are 10slots in a radio frame in this case. For SCS of 30 KHz it can be set to20 as there 20 slots in a radio frame in this case. For SCS of 60 KHz itcan be set to 40 as there are 40 slots in a radio frame in this case.For SCS of 120 KHz it can be set to 80 as there are 80 slots in a radioframe in this case.

In an embodiment, if maximum size of RAR window is greater than oneradio frame called N radio frames, then slots in every N consecutiveradio frames starting from radio frame with SFN 0, are indexedsequentially from zero. Slots in SFN 0 to SFN N−1 are indexedsequentially start from zero. Slots in SFN N to SFN 2N−1 are indexedsequentially start from zero and so on as shown in FIG. 19 below. Inthis case X2 can be equal to 80*N, as maximum number of slots in radioframe is 80 and maximum number of slots in N radio frames is N*80. Theslots are indexed sequentially for N consecutive radio frames startingfrom first slot of every radio frame with SFN which satisfies equationSFN mod N=0.

In another embodiment, if maximum size of RAR window is greater than oneradio frame called N sub frames, then slots in N consecutive sub framesstarting from 1st subframe in radio frame with SFN 0, are indexedsequentially from zero. Slots in subframe 0 to subframe N−1 are indexedsequentially start from zero. Slots in subframe N to subframe 2N−1 areindexed sequentially starting from zero and so on as shown in FIG. 20below. In this case X2 can be equal to 8*N as maximum number of slots ina subframe is 8. The slots are indexed sequentially for N subframesframes starting from first slot of every subframe ‘i’ in radio frame ‘j’which satisfies equation (j*10+i) mod N=0, where ‘j’ is the SFN of radioframe and ‘i’ is the subframe index (with radio frame subframes areindexed from 0 to 9 sequentially) of subframe within a radio frame.

In another embodiment, if maximum size of RAR window is called N slots,then starting from 1st slot of SFN 0, every N consecutive slots areindexed sequentially from zero to N−1 as shown in FIG. 21 . In this caseX2 can be equal to N.

In this example, f_id is an index of the PRACH transmission occasion, inascending order of frequency domain; 0≤f_id<Y; and Y depends on numberof RACH transmission occasions supported in frequency domain in NR. Inan embodiment, if multiple resource pools (e.g. separate resource poolfor beam failure recovery, handover, etc.) for RACH are configured,frequency division multiplexed PRACH transmission occasions in eachresource pool can be independently numbered starting from zero. Forexample, if there are two resource pools, resource pool 1 having twofrequency division multiplexed PRACH transmission occasions and resourcepool 2 having four frequency division multiplexed PRACH transmissionoccasions, the frequency division multiplexed PRACH transmissionoccasions are numbered 0 and 1 in resource pool 1 and the frequencydivision multiplexed PRACH transmission occasions are numbered 0, 1, 2,and 3 in resource pool 2.

In another embodiment, if multiple resource pools for RACH areconfigured, frequency division multiplexed PRACH transmission occasionsare numbered starting from zero across resource pools. For example, letus say there are two resource pools. In resource pool 1 there are twofrequency division multiplexed PRACH transmission occasions. In resourcepool 2 there are four frequency division multiplexed PRACH transmissionoccasions. The frequency division multiplexed PRACH transmissionoccasions are numbered 0 and 1 in resource pool 1. The frequencydivision multiplexed PRACH transmission occasions are numbered 2, 3, 4,and 5. In another embodiment, if multiple resource pools for RACH areconfigured, network may configure the starting f_id to be used for eachresource pool. The FDM PRACH transmission occasions in a resource poolare sequentially numbered starting from f_id indicated by network forthat resource pool.

In this example, P_id is a value of Z Msbs of Random Access PreambleIdentifier of Random access preamble transmitted by UE. Z ispre-defined. For example if Z is 2 bits, then P_id is 0 (if 2 Msbs ofRandom Access Preamble Identifier are ‘00’) or 1 (if 2 Msbs of RandomAccess Preamble Identifier are ‘01’) or 2 (if 2 Msbs of Random AccessPreamble Identifier are ‘10’) or 3 (if 2 Msbs of Random Access PreambleIdentifier are ‘11’).

Note that other combinations, with respect to position of t_id1, t_id2,f_id and P_id in RA-RNTI equation are also possible. Various ways ofcomputing RA-RNTI based on t_id1, t_id2, f_id and P_id are as follows:

RA-RNTI=1+Parameter 1+C1*Parameter 2+C1*C2*Parameter3+C1*C2*C3*Parameter 4

In this example, Parameter 1 is one of t_id1, t_id2, f_id, or P_id,Parameter 2 is one of [{t_id 1, t_id2, f_id, P_id}−{Selected Parameter1}], Parameter 3 is one of [{t_id1, t_id2, f_id, P_id}−{SelectedParameter 1}−{Selected Parameter 2}], Parameter 4 is one of [{t_id1,t_id2, f_id, P_id}−{Selected Parameter 1}−{Selected Parameter2}−{Selected Parameter 3}], C1 is a number of distinct values ofSelected parameter 1, C2 is a number of distinct values of Selectedparameter 2, and C3 is a number of distinct values of Selected parameter3.

In another embodiment, random access preamble can be transmitted onfrequency F1 and RAR can be received on frequency F2. In this caseinformation about the carrier on which random access preamble istransmitted can also be included in RA-RNTI computation. For example,serving cell can configure a supplementary uplink (SUL) frequency calledFy. The uplink frequency of serving cell is called Fx. Serving cellconfigures PRACH resources on frequency Fy and Fx. Based on certaincriteria UE selects PRACH resource on either frequency Fy or frequencyFx for random access preamble transmission. If UE transmits randomaccess preamble on frequency Fy, it receives RAR in DL of serving cell.If the UE transmits random access preamble on frequency Fx, it receivesRAR in DL of serving cell. The RA-RNTI can be computed as follows:

RA-RNTI=1+t_id1+X1*t_id2+X1*X2*f_id+X1*X2*Y*c_id+X1*X2*Y*2*P_id

OR

RA-RNTI=1+t_id1+X1*t_id2+X1*X2*f_id+X1*X2*Y*P_id+X1*X2*Y*2Z*c_id

OR

RA-RNTI=1+P_id+2Z*t_id1+X1*2Z*t_id2+X1*2Z*X2*f_id+X1*X2*Y*2Z*c_id

OR

RA-RNTI=1+t_id1+X1*P_id+X1*2Z*t_id2+X1*2Z*X2*f_id+X1*X2*Y*2Z*c_id

OR

RA-RNTI=1+t_id1+X1*t_id2+X1*X2*P_id+X1*X2*2Z*f_id+X1*X2*Y*2Z*c_id

In this example, the values of t_id1, t_id2, f_id, P_id, X1, X2, Z and Yare explained earlier. The value of c_id is set to ‘1’ if UE transmitsrandom access preamble on SUL or else c_id is set to ‘0.’ In anembodiment, the value of c_id to be used specific to a carrier frequency(or specific to serving cell) on which random access preamble istransmitted can be signaled by network. This can be signaled in systeminformation or in dedicated signaling. A list of mapping between c_idand carrier frequency can be signaled. The UE uses the c_idcorresponding to carrier frequency on which it has transmitted randomaccess preamble. In an embodiment value of c_id for PCell and PSCell iszero. The value of c_id for a SCell other than PSCell is signaled bynetwork in SI or dedicated signaling. Alternatively, the value of c_idfor a SCell other than PSCell is equal to serving cell index.

Note that other combinations, with respect to position of t_id1, t_id2,f_id, P_id and c_id in RA-RNTI equation are also possible. Various waysof computing RA-RNTI based on t_id1, t_id2, f_id, P_id and c_id are asfollows:

RA-RNTI=1+Parameter 1+C1*Parameter 2+C1*C2*Parameter3+C1*C2*C3*Parameter 4+C1*C2*C3*C4*Parameter 5

In this example, Parameter 1 is one of t_id1, t_id2, f_id, P_id, orc_id, Parameter 2 is one of [{t_id1, t_id2, f_id, P_id, c_id}−{SelectedParameter 1}], Parameter 3 is one of [{t_id1, t_id2, f_id, P_id,c_id}−{Selected Parameter 1}−{Selected Parameter 2}], Parameter 4 is oneof [{t_id1, t_id2, f_id, P_id, c_id}-{Selected Parameter 1}−{SelectedParameter 2}−{Selected Parameter 3}], Parameter 5 is one of [{t_id1,t_id2, f_id, P_id, c_id}−{Selected Parameter 1}−{Selected Parameter2}−{Selected Parameter 3}−{Selected Parameter 4}], C1 is a number ofdistinct values of Selected parameter 1, C2 is a number of distinctvalues of Selected parameter 2, C3 is a number of distinct values ofSelected parameter 3, and C4 is a number of distinct values of Selectedparameter 4.

Method 2

In this scenario, each OFDM symbol can be a transmission occasion in aslot. The RA-RNTI associated with the PRACH in which the Random AccessPreamble is transmitted, is computed as:

RA-RNTI=1+t_id1+X1*t_id2+X1*X2*t_id3+X1*X2*X3*f_id+X1*X2*X3*Y*P_id

In this example, t_id1 is an index of the first OFDM symbol of the PRACHtransmission occasion (0≤t_id1<X1) and t_id2 is an index of the firstslot of the PRACH transmission occasion, i.e., a slot in which RACHtransmission occasion starts (0≤t_id2<X2). The value of X1 can be 14,since each slot has 14 OFDM symbols and PRACH transmission occasion canstart in any symbol. OFDM symbols in a slot are indexed sequentiallystarting from zero. If PRACH transmission occasion can start only insome symbols in a slot, X1 can be smaller than 14. For example, if PRACHtransmission occasion can only start in symbols 0, 4, 8 and 12, X1 canbe 4. Each of these symbols (e.g. 0, 4, 8, 12) where PRACH transmissionoccasion can start are logically indexed sequentially i.e. T_id1 forRACH transmission occasion starting in symbol 0 is 0, T_id1 for RACHtransmission occasion starting in symbol 4 is 1, T_id1 for RACHtransmission occasion starting in symbol 8 is 2 and T_id1 for RACHtransmission occasion starting in symbol 12 is 3.

The maximum number of slots in a subframe is 8, so X2 can be equal to 8;slots in subframe are indexed sequentially starting from zero.

Alternately, if PRACH transmission occasion can start only in some slotsin a sub frame, X2 can be smaller than 8. For example, if PRACHtransmission occasion can only start in slot 0 and 4, X2 can be 4. Eachof these slots (e.g. 0, 4) where PRACH transmission occasion can startcan be logically indexed sequentially (i.e. T_id2 for RACH transmissionoccasion starting in slot 0 is 0, T_id2 for RACH transmission occasionstarting in slot 4 is 1).

In an embodiment, X2 can be set to a value depending on numerology orSCS. For example for SCS of 15 KHz it can be set to 1 as there is 1slots in a sub frame in this case. For SCS of 30 KHz it can be set to 2as there 2 slots in a sub frame in this case. For SCS of 60 KHz it canbe set to 4 as there are 4 slots in a sub frame in this case. For SCS of120 KHz it can be set to 8 as there are 8 slots in a sub frame in thiscase.

t_id 3 is an index of the subframe in which PRACH transmission occasionstarts or subframe in which first slot of PRACH transmission occasion islocated; 0<t_id 3<X3; The subframes in a radio frame are sequentiallynumbered starting from zero. Maximum number of subframe in a radio frameis 10, so X3 can be equal to 10 if the maximum RAR window size is oneradio frame;

In this example, f_id is an index of the PRACH transmission occasion, inascending order of frequency domain; 0≤f_id<Y; Y depends on number ofRACH transmission occasions supported in frequency domain in NR. In anembodiment, if multiple resource pools (e.g. separate resource pool forbeam failure recovery, handover, etc.) for RACH are configured,frequency division multiplexed PRACH transmission occasions in eachresource pool can be independently numbered starting from zero. Forexample, if there are two resource pools, resource pool 1 having twofrequency division multiplexed PRACH transmission occasions and resourcepool 2 having four frequency division multiplexed PRACH transmissionoccasions, the frequency division multiplexed PRACH transmissionoccasions are numbered 0 and 1 in resource pool 1 and the frequencydivision multiplexed PRACH transmission occasions are numbered 0, 1, 2,and 3 in resource pool 2.

In another embodiment, if multiple resource pools for RACH areconfigured, frequency division multiplexed PRACH transmission occasionsare numbered starting from zero across resource pools. For example, letus say there are two resource pools. In resource pool 1 there are twofrequency division multiplexed PRACH transmission occasions. In resourcepool 2 there are four frequency division multiplexed PRACH transmissionoccasions. The frequency division multiplexed PRACH transmissionoccasions are numbered 0 and 1 in resource pool 1. The frequencydivision multiplexed PRACH transmission occasions are numbered 2, 3, 4,and 5. In another embodiment, if multiple resource pools for RACH areconfigured, network may configure the starting f_id to be used for eachresource pool. The FDM PRACH transmission occasions in a resource poolare sequentially numbered starting from f_id indicated by network forthat resource pool.

In another embodiment, if maximum size of RAR window is greater than oneradio frame called N radio frames, then subframes in N consecutive radioframes starting from radio frame with SFN 0 are indexed sequentiallyfrom zero. Subframes in SFN 0 to SFN N−1 are indexed sequentially startfrom zero. Subframes in SFN N to SFN 2N−1 are indexed sequentially startfrom zero and so on as shown in FIG. 21 below. In this case X3 can beequal to 10*N. The subframes are indexed sequentially for N radio framesstarting from first subframe of every radio frame with SFN whichsatisfies equation SFN mod N=0.

In an embodiment, if maximum size of RAR window is greater than oneradio frame called N sub frames, then every N consecutive subframes inSFN cycle, starting from the first subframe of radio frame with SFN 0,are indexed sequentially starting from zero as shown in FIG. 23 . Inthis case X3 can be equal to N.

P_id is a value of Z Msbs of Random Access Preamble Identifier of Randomaccess preamble transmitted by UE. Z is pre-defined. For example if Z is2 bits, then P_id is 0 (if 2 Msbs of Random Access Preamble Identifierare ‘00’) or 1 (if 2 Msbs of Random Access Preamble Identifier are ‘01’)or 2 (if 2 Msbs of Random Access Preamble Identifier are ‘10’) or 3 (if2 Msbs of Random Access Preamble Identifier are ‘11’).

Note that other combinations, with respect to position of t_id1, t_id2,t_id3, f_id and P_id in RA-RNTI equation are also possible. Various waysof computing RA-RNTI based on t_id1, t_id2, t_id3, f_id and P_id are asfollows:

RA-RNTI=1+Parameter 1+C1*Parameter 2+C1*C2*Parameter3+C1*C2*C3*Parameter 4+C1*C2*C3*C4*Parameter 5

In this example, Parameter 1 is one of t_id1, t_id2, t_id3, f_id, orP_id, Parameter 2 is one of [{t_id1, t_id2, t_id3, f_id, P_id}−{SelectedParameter 1}], Parameter 3 is one of [{t_id1, t_id2, t_id3, f_id,P_id}−{Selected Parameter 1}−{Selected Parameter 2}], Parameter 4 is oneof [{t_id1, t_id2, t_id3, f_id, P_id}-{Selected Parameter 1}−{SelectedParameter 2}−{Selected Parameter 3}], Parameter 5 is one of [{t_id1,t_id2, t_id3, f_id, P_id}−{Selected Parameter 1}−{Selected Parameter2}−{Selected Parameter 3}−{Selected Parameter 4}], C1 is a number ofdistinct values of Selected parameter 1, C2 is a number of distinctvalues of Selected parameter 2, C3 is a number of distinct values ofSelected parameter 3, and C4 is a number of distinct values of Selectedparameter 4

In another embodiment, random access preamble can be transmitted onfrequency F1 and RAR can be received on frequency F2. In this caseinformation about the carrier on which random access preamble istransmitted can also be included in RA-RNTI computation. For example,serving cell can configure a supplementary uplink (SUL) frequency calledFy. The uplink frequency of serving cell is called Fx. Serving cellconfigures PRACH resources on frequency Fy and Fx. Based on certaincriteria UE selects PRACH resource on either frequency Fy or frequencyFx for random access preamble transmission. If UE transmits randomaccess preamble on frequency Fy, it receives RAR in DL of serving cell.If the UE transmits random access preamble on frequency Fx, it receivesRAR in DL of serving cell. The RA-RNTI can be computed as follows:

RA-RNTI=1+t_id1+X1*t_id2+X1*X2*t_id3+X1*X2*X3*f_id+X1*X2*X3*Y*P_id+X1*X2*X3*Y*2Z*c_id

In this example, t_id1, t_id2, t_id3, f_id, P_id, X1, X2, X3, Z and Yare same as explained earlier. The value of c_id is set to ‘1’ if UEtransmits random access preamble on SUL or else c_id is set to ‘0.’

In an embodiment, the value of c_id to be used specific to a carrierfrequency (or specific to serving cell) on which random access preambleis transmitted can be signaled by network. This can be signaled insystem information or in dedicated signaling. A list of mapping betweenc_id and carrier frequency can be signaled. The UE uses the c_idcorresponding to carrier frequency on which it has transmitted randomaccess preamble. In an embodiment, value of c_id for PCell and PSCell iszero. The value of c_id for a SCell other than PSCell is signaled bynetwork in SI or dedicated signaling. Alternatively, the value of c_idfor a SCell other than PSCell is equal to serving cell index.

Note that other combinations, with respect to position of t_id1, t_id2,t_id3, f_id, P_id and c_id in RA-RNTI equation are also possible.Various ways of computing RA-RNTI based on t_id1, t_id2, t_id3, f_id,P_id and c_id are as follows:

RA-RNTI=1+Parameter 1+C1*Parameter 2+C1*C2*Parameter3+C1*C2*C3*Parameter 4+C1*C2*C3*C4*Parameter 5+C1*C2*C3*C4*C5*Parameter6

In this example, Parameter 1 is one of t_id1, t_id2, t_id3, f_id, P_id,or c_id, Parameter 2 is one of [{t_id1, t_id2, t_id3, f_id, P_id,c_id}−{Selected Parameter 1}], Parameter 3 is one of [{t_id1, t_id2,t_id3, f_id, P_id, c_id}−{Selected Parameter 1}−{Selected Parameter 2}],Parameter 4 is one of [{t_id1, t_id2, t_id3, f_id, P_id, c_id}−{SelectedParameter 1}−{Selected Parameter 2}−{Selected Parameter 3}], Parameter 5is one of [{t_id1, t_id2, t_id3, f_id, P_id, c_id}−{Selected Parameter1}−{Selected Parameter 2}−{Selected Parameter 3}−{Selected Parameter4}], Parameter 6 is one of [{t_id1, t_id2, t_id3, f_id, P_id,c_id}−{Selected Parameter 1}−{Selected Parameter 2}−{Selected Parameter3}−{Selected Parameter 4}−{Selected Parameter 5}], C1 is a number ofdistinct values of Selected parameter 1, C2 is a number of distinctvalues of Selected parameter 2, C3 is a number of distinct values ofSelected parameter 3, C4 is a number of distinct values of Selectedparameter 4, and C5 is a number of distinct values of Selected parameter5.

FIG. 27 illustrates an eNB apparatus according to an embodiment to thedisclosure.

Referring to FIG. 27 , the eNB 2700 includes a transceiver 2710, acontroller 2720 and a memory 2730. Alternatively, the transceiver may beimplemented as a transmitter and a receiver, and each component may beimplemented through one or more processors. The transceiver can receiverandom access preamble and scheduled transmission from a UE and transmitNR-PDCCH addressed to RA-RNTI and NR-PDSCH including random accessresponse to the UE. The memory can store information associated withrandom access procedure. The controller is configured to identifyRA-RNTI and generate random access response based on received randomaccess preamble and control the transceiver and the memory according toembodiments of the disclosure.

FIG. 28 illustrates a UE according to an embodiment of the disclosure.

Referring to FIG. 28 , the UE 2800 includes a transceiver 2810, acontroller 2820 and a memory 2830. Alternatively, the transceiver may beimplemented as a transmitter and a receiver, and each component may beimplemented through one or more processors. The transceiver can receiverandom access response and transmit random access preamble and scheduledtransmission. The memory can store information associated with randomaccess procedure. The controller is configured to identify RA-RNTI basedon transmitted random access preamble and information included in randomaccess response and control the transceiver and the memory according toembodiments of the disclosure.

The above-described embodiments of the disclosure and the accompanyingdrawings have been provided only as specific examples in order to assistin understanding the disclosure and do not limit the scope of thedisclosure. Accordingly, those skilled in the art to which thedisclosure pertains will understand that other change examples based onthe technical idea of the disclosure may be made without departing fromthe scope of the disclosure.

While the disclosure has been shown and described with reference tovarious embodiments thereof, it will be understood by those skilled inthe art that various changes in form and details may be made thereinwithout departing from the spirit and scope of the disclosure as definedby the appended claims and their equivalents.

What is claimed is:
 1. A method performed by a terminal in a wirelesscommunication system, the method comprising: transmitting a randomaccess preamble to a base station; receiving a random access response(RAR) medium access control (MAC) protocol data unit (PDU) including aplurality of MAC subPDUs from the base station; identifying whether afirst MAC subPDU includes a random access preamble identifier (RAPID)which corresponds to the transmitted random access preamble; and in casethat the RAPID in the first MAC subPDU corresponds to the RAPID of thetransmitted random access preamble, identifying whether the RAPID in thefirst MAC subPDU corresponds to one of RAPIDs for system information(SI) request, and identifying a presence of a MAC RAR in the first MACsubPDU based on whether the RAPID in the first MAC subPDU corresponds toone of the RAPIDs for SI request or not.
 2. The method of claim 1,further comprising: determining whether a second MAC subPDU is presentafter the first MAC subPDU, wherein the second MAC subPDU is presentafter the first MAC subPDU in case that extension information in thefirst MAC subPDU is set to 1, and the second MAC subPDU is not presentafter the first MAC subPDU in case that the extension information in thefirst MAC subPDU is set to
 0. 3. The method of claim 1, furthercomprising: identifying whether the first MAC subPDU includes a backoffindicator or the RAPID based on type information in the first MACsubPDU.
 4. The method of claim 1, wherein the MAC RAR is included in thefirst MAC subPDU in case that the RAPID in the first MAC subPDU does notcorrespond to one of the RAPIDs for SI request, and the MAC RAR is notincluded in the first MAC subPDU in case that the RAPID in the first MACsubPDU corresponds to one of the RAPIDs for SI request.
 5. The method ofclaim 1, wherein one or more RAPIDs for SI request are signaled by thebase station.
 6. The method of claim 1, wherein the MAC subPDUs includeone of a backoff indicator subheader, a RAPID subheader for SI requestacknowledgement or a RAPID subheader and corresponding MAC RAR.
 7. Themethod of claim 6, wherein the backoff indicator is included in abeginning of the RAR MAC PDU.
 8. The method of claim 6, wherein theRAPID subheader for SI request acknowledgement includes extensioninformation, type information and the RAPID indicating the transmittedrandom access preamble from the terminal.
 9. A method performed by abase station in a wireless communication system, the method comprising:receiving a random access preamble from a terminal; and transmitting arandom access response (RAR) medium access control (MAC) protocol dataunit (PDU) including a plurality of MAC subPDUs to the terminal, whereinthe MAC subPDUs include one of a backoff indicator subheader, a randomaccess preamble identifier (RAPID) subheader for system information (SI)request acknowledgement or a RAPID subheader and corresponding MAC RAR.10. The method of claim 9, wherein the backoff indicator is included ina beginning of the RAR MAC PDU.
 11. The method of claim 9, wherein theRAPID subheader for SI request acknowledgement includes extensioninformation, type information and the RAPID indicating the receivedrandom access preamble from the terminal.
 12. The method of claim 9,wherein one or more RAPIDs for SI request are signaled to the terminal.13. A terminal in a wireless communication system, the terminalcomprising: a transceiver; and a controller coupled with the transceiverand configured to: transmit a random access preamble to a base station,receive a random access response (RAR) medium access control (MAC)protocol data unit (PDU) including a plurality of MAC subPDUs from thebase station, identify whether a first MAC subPDU includes a randomaccess preamble identifier (RAPID) which corresponds to the transmittedrandom access preamble, and in case that the RAPID in the first MACsubPDU corresponds to the RAPID of the transmitted random accesspreamble, identify whether the RAPID in the first MAC subPDU correspondsto one of RAPIDs for system information (SI) request, and identify apresence of a MAC RAR in the first MAC subPDU based on whether the RAPIDin the first MAC subPDU corresponds to one of the RAPIDs for SI requestor not.
 14. The terminal of claim 13, further comprising: determiningwhether a second MAC subPDU is present after the first MAC subPDU,wherein the second MAC subPDU is present after the first MAC subPDU incase that extension information in the first MAC subPDU is set to 1, andthe second MAC subPDU is not present after the first MAC subPDU in casethat the extension information in the first MAC subPDU is set to
 0. 15.The terminal of claim 13, further comprising: identifying whether thefirst MAC subPDU includes a backoff indicator or the RAPID based on typeinformation in the first MAC subPDU.
 16. The terminal of claim 13,wherein the MAC RAR is included in the first MAC subPDU in case that theRAPID in the first MAC subPDU does not correspond to one of the RAPIDsfor SI request, and the MAC RAR is not included in the first MAC subPDUin case that the RAPID in the first MAC subPDU corresponds to one of theRAPIDs for SI request.
 17. The terminal of claim 13, wherein one or moreRAPIDs for SI request are signaled by the base station.
 18. The terminalof claim 13, wherein the MAC subPDUs include one of a backoff indicatorsubheader, a RAPID subheader for SI request acknowledgement or a RAPIDsubheader and corresponding MAC RAR.
 19. The terminal of claim 18,wherein the backoff indicator is included in a beginning of the RAR MACPDU.
 20. The terminal of claim 18, wherein the RAPID subheader for SIrequest acknowledgement includes extension information, type informationand the RAPID indicating the transmitted random access preamble from theterminal.
 21. A base station in a wireless communication system, thebase station comprising: a transceiver; and a controller coupled withthe transceiver and configured to: receive a random access preamble froma terminal, and transmit a random access response (RAR) medium accesscontrol (MAC) protocol data unit (PDU) including a plurality of MACsubPDUs to the terminal, wherein the MAC subPDUs include one of abackoff indicator subheader, a random access preamble identifier (RAPID)subheader for system information (SI) request acknowledgement or a RAPIDsubheader and corresponding MAC RAR.
 22. The base station of claim 21,wherein the backoff indicator is included in a beginning of the RAR MACPDU.
 23. The base station of claim 21, wherein the RAPID subheader forSI request acknowledgement includes extension information, typeinformation and the RAPID indicating the received random access preamblefrom the terminal.
 24. The base station of claim 21, wherein one or moreRAPIDs for SI request are signaled to the terminal.